Takeoff and Landing Performance Optimization

Transcription

1 Takeoff and Landing Performance Optimization Development of a Computional Methodology João Pedro Rodrigues de Lemos Viana Dissertation submitted to obtain the Master s Degree in Aerospace Engineering Jury Chair: Supervisor: External examiner: Prof. Fernando José Parracho Lau Prof. António José Nobre Martins Aguiar Prof. Pedro da Graça Tavares Alvares Serrão October 2011

2 Acknowledgments It is a pleasure to thank those who have contributed to the realization of this dissertation: Daniela Vasco, my girlfriend, who has always supported me, especially in the later stages of this work. Thank you for your patience. António Aguiar, Engr., my supervisor, for giving me the chance to take part in such an interesting project and, also, for the amount of time and close attention to detail he has always offered when coordinating this project. Carlos Figueiredo, one of the lead engineers on TAP s Electronic Flight Bag project, who has played a major role in this work, never hesitating in grating me some of his valuable time. António Messias, Engr., Pedro Faria Pereira, Engr., and Paulo Marques, who provided utmost important feedback during the development of this project. Notwithstanding all the people that made my experience more enjoyable at TAP during the last six months, namely Bruno Moreira, David Afonso, Marília Santos, Ana Maria Sousa, Amélia Santos, Ivo Santos and Belinda Cardoso. i

3 Abstract During the past decades the global aviation industry has been experiencing a precarious balance between revenue and costs. Besides, the modern world is living an economic recession and so crude prices are now higher than ever. Therefore, all over the world, airlines need to adapt and evolve, finding new ways of struggling through the competitive world of commercial aviation. Optimization is currently the key to succeed. Aircraft performance data calculation and optimization reflects through the whole airline operation. Besides having flight safety as its ultimate concern, data availability and easy recalculation makes airlines operation more safeguarded to operation disruptions due to external agents. Also, the quality of this data reflects in the airlines balance sheets at the end of the year as the result of possible savings in different areas of operation [1]. The present work focuses in the development of a computational application for takeoff and landing performance data generation and optimization. The takeoff performance optimization entails the maximization of the Regulatory TakeOff Weight (RTOW) and the respective operational speeds (V 1, V R and V 2 ). In a similar way, the Regulatory Landing Weight (RLW), the final approach speed (V FA ) and the landing distances (actual and required) are computed during the landing optimization. The results are to be automatically published in the form of RTOW and RLW charts. The actual calculations are processed by Airbus Operational and Certified TakeOff and landing Performance Universal Software (OCTOPUS). The developed application is more than a simple program; it handles a set of TAP s databases and external programs with the single objective of providing customized aircraft performance optimization capabilities, at the distance of one click, to TAP s personnel. Keywords: Aircraft Performance; Performance Software; Takeoff Optimization; Landing Optimization; OCTOPUS. ii

4 Resumo Ao longo das últimas décadas, o sector da aviação tem vivido num equilíbrio precário entre receitas e despesas. A economia mundial está actualmente em recessão e os preços do petróleo estão mais altos do que nunca. Tendo isto em conta, as companhias aéreas precisam de se adaptar e evoluir, de modo a encontrar novas formas de vencerem no mundo competitivo da aviação comercial. A optimização é, hoje, a chave para o sucesso. O cálculo e optimização dos dados de desempenho aeronáutico reflectem-se através de toda a cadeia de operação das companhias aéreas. Para além de ter a segurança do voo como derradeiro objectivo, a disponibilização e fácil actualização destes dados torna as companhias aéreas mais protegidas contra agentes externos. A qualidade dos mesmos reflecte-se no final do ano, podendo reduzir as despesas em diversas áreas de operação [1]. O presente trabalho foca-se no desenvolvimento de uma aplicação computacional para produção e optimização de dados de desempenho à descolagem e aterragem. A optimização do desempenho à descolagem pressupõe a maximização do peso regulamentado à descolagem (RTOW Regulatory TakeOff Weight) e as respectivas velocidades operacionais (V 1, V R e V 2 ). De forma semelhante, o peso máximo regulamentado à aterragem (RLW Regulatory Landing Weight), a velocidade final de aproximação (V FA ) e as distâncias de aterragem (concreta e necessária) são calculadas durante a optimização de aterragem. Os resultados devem ser publicados sob a forma de tabelas de RTOW e RLW. Os cálculos por detrás da optimização são efectuados por um programa oficial da Airbus OCTOPUS (Operational and Certified TakeOff and landing Universal Software). A aplicação desenvolvida é mais do que um simples programa, lidando com diversas bases de dados da TAP e interagindo com programas externos. O objectivo final do projecto é proporcionar capacidades personalizadas de optimização de desempenho aeronáutico a engenheiros e pilotos. Palavras-chave: Desempenho Aeronáutico; Software de Desempenho; Optimização de Descolagem; Optimização de Aterragem; OCTOPUS. iii

5 Table of Contents Acknowledgments... 1 Abstract... 2 Resumo... 3 Table of Contents... 4 List of Figures... 6 List of Tables... 8 List of Acronyms Introduction Economic Scenario Relevance Airlines Operational Context Objectives Dissertation Structure TAP s Case Study Flight Dispatch Flight Operations Engineering Department Remarks Aircraft Performance Aircraft Settings Aircraft Limitations Takeoff Performance Operational Speeds Runway Obstacles and Takeoff Trajectory Outside Elements Limitation Summary Takeoff Optimization Optimization Range Free Parameters Influence Optimization Process Flexible Takeoff Landing Performance Operational Speeds Runway Go-Around Requirements iv

6 6.4. Outside Elements Limitation Summary Takeoff and Landing Performance Application (TLP) Structure User Interface Overview Databases and Internal Classes Relevant Routines OCTOPUS Testing and Validation Conclusion References APPENDIX A Regulation Transcripts APPENDIX B Performance on Wet and Contaminated Runways APPENDIX C TLP APPENDIX D FAJS-21R APPENDIX E FM Page - A APPENDIX F Obstacles Limitation Verification APPENDIX G PEP-FM Files v

7 List of Figures Figure 1 - (a) Jet Fuel costs in the US Figure 1 - (b) Overall Airline Costs Mirroring Fuel Price Changes Figure 2 - High-lift devices on an Airbus A Figure 3 - Simple (a) and fowler (b) trailing edge flaps Figure 4 - Slat Figure 5 - Flaps lever Figure 6 - Environmental Control Systems for the A320 family Figure 7 - CL versus angle of attack Figure 8 - V MCG Figure 9 - (a) Sideslip angle Figure 9 - (b) in a one-engine-inoperative condition Figure 10 - V MU determination Figure 11 - Aircraft Weights Figure 12 - A Environmental Envelope Figure 13 - TOGA thrust versus OAT and PA for a given engine type Figure 14 - Takeoff Profile Figure 15 - Decision Speed Figure 16 - Takeoff Speed Summary and Limitations related to V 1, V R, V LOF and V Figure 17 - Stopway Figure 18 - Clearway Figure 19 - Available Takeoff Lengths Figure 20 - Lineup Adjustment, Top Figure 21 - Lineup Adjustment, Side Figure 22 - Runway slope effect on takeoff performance Figure 23 - Takeoff Path and Definition of Various Segments Figure 24 - Gross and net takeoff paths Figure 25 - Departure Sector for track changes under Figure 26 - Departure Sector for track changes over Figure 27 - Headwind determination Figure 28 - Headwind effect on ground speed Figure 29 - Pressure altitude effect on takeoff performance Figure 30 - Takeoff Performance Limitations Figure 31 - Takeoff configurations performance Figure 32 - Runway Limited MTOW Figure 33 - (a) Effect of V 2 /V S in the obstacles, takeoff segments Figure 33 - (b) Effect of V 2 /V S in the brake energy and tire speed limitations Figure 34 - Optimum V 1 /V R Figure 35 - MTOW as function of V 1 /V R and V 2 /V S Figure 36 - Range of soultions that maximize MTOW Figure 37 - Takeoff speeds calculation Figure 38 - Flexible temperature principle Figure 39 - Obstacle influence on LDA Figure 40 - Actual Landing Distance Figure 41 - Airborne phase for an automatic landing Figure 42 - Ground role phase for an automatic landing Figure 43 - Go-around procedure Figure 44 - Pressure altitude influence in the landing performance Figure 45 - TLP structure vi

8 Figure 46 - Please Wait animated message running in an additional thread Figure 47 - TLP on startup Figure 48 - Aircraft page for the Takeoff Optimization mode Figure 49 - Aircraft Failures form Figure 50 - Runway page for the Takeoff Optimization mode Figure 51 - Options page for the Takeoff Optimization mode Figure 52 - Calculation page for the Takeoff Optimization mode Figure 53 - Temperature vector Figure 54 - TLP s Output for the Takeoff Optimization mode Figure 55 - Pressure Altitude function of Pressure Figure 56 - OCTOPUS Structure Figure 57 - OCTOPUS Functions Figure 58 - Aircraft braking coefficient for a 200 psi tire pressure on a wet runway Figure 59 - Aircraft braking coefficient on a wet runway Figure 60 - Physics of contaminant drag Figure 61 - Displacement Drag Figure 62 - Impingment Drag Figure 63 - Hydroplaning effect Figure 64 - Effect of contaminants on takeoff distances vii

9 List of Tables Table 1 - A320 family Flap and Slat configurations... 7 Table 2 - A CDL Table 3 - Thrust Setting and EGT Limit for an A (CFM56-5C3 engine) Table 4 - Lineup Adjustments for 90 Runway Entry Table 5 - Takeoff Segments Characteristics Table 6 - Minimum height to start a track change according to wingspan Table 7 - Semi-width ( E 0 ) at the Start of the Departure Sector Table 8 - Wet and contaminated runways Table 9 - TAP s takeoff limitations Table 10 - Influencing Parameters Table 11 - V 2 /V S maximum values for the Airbus family Table 12 - Influence of V 2 /V S ratio on takeoff limitations Table 13 - Minimum climb gradients during approach climb (OEI) Table 14 - Landing limitations Table 15 - Aircraft models and respective databases Table 16- TLP s takeoff optimization results Table 17 - Selected runways lengths Table 18 - AFM s takeoff results Table 19 - Optimum weights and ratios obtained by PEP s TLO module Table 20 - TLP landing optimization results Table 21 - Required Landing Distance calculated by FM s Landing Distance function Table 22 - ALD calculated by FM s Operational Landing Distance function Table 23 - Maximum weight calculated by FM s Landing Climb Gradient function Table 24 - Maximum weight calculated by FM s Approach Climb Gradient function viii

10 List of Acronyms ACARS Aircraft Communication and Reporting System ACG Approach Climb Gradient AEO All Engines Operating AFM Aircraft Flight Manual ALD Actual Landing Distance API Application Interface ASD Accelerate-Stop Distance ASDA Accelerate Stop Distance Available ATA Air Transport Association of America ATOW Actual Takeoff Weight CDL Configuration Deviation List CL Climb Lift coefficient CWY Clearway Da Airborne Phase DB Database Dg Ground Phase DOW Dry Operating Weight EASA European Aviation Safety Agency ECS Environmental Control System EFB Electronic Flight Bag EGT Exhaust Gas Temperature FAA Federal Aviation Administration FBW Fly-By-Wire FCOM Flight Crew Operating Manual HW Headwind component ICAO International Civil Aviation Organization ISA International Standard Atmosphere JAA Joint Aviation Authority LD Landing Distance LW Landing Weight MCT Maximum Continuous Thrust MEL Minimum Equipment List MEW Manufacturer s Empty Weight MLW Maximum Structural Landing Weight MSL Mean Sea Level MTOW Maximum Structural Takeoff Weight OAT Outside Air Temperature OCTOPUS Operational and Certified TakeOff and landing Performance Universal Software OEI One Engine Inoperative OEW Operational Empty Weight OLE Object Linking and Embedding PEP Performance Engineer s Programs QNH Local mean sea level atmospheric pressure setting (Q-code system) RLD Required Landing Distance RLW Regulatory Landing Weight RTO Rejected Takeoff RTOW Regulatory Takeoff Weight ix

11 RWY S SWY TAS TLO TLP TOD TODA TOR TORA TOGA TOW T Flex T Flex Max T MAX T REF V V 1 V 2 V FA V EF V LOF V LS V MBE V MCA V MCG V MCL V MU V R V REF V S V SR V S1g V TD V TIRE ZFW Runway Aerodynamic reference wing area Stopway True Air Speed Takeoff and Landing Optimization Takeoff and Landing Performance Program Takeoff Distance Takeoff Distance Available Takeoff Run Takeoff Runway Available TakeOff-Go-Around Takeoff Weight Flexible Temperature Maximum Flexible Temperature Maximum Operational Temperature Reference Temperature (or flat rated temperature) Airspeed Decision Speed Takeoff Climb Speed Final Approach Speed Engine Failure Speed Lift-off Speed Lowest Selectable Speed Maximum Brake Energy Speed Minimum Control Speed in the Air Minimum Control Speed on the Ground Minimum Speed During Approach and Landing Minimum Unstick Speed Rotation Speed Reference Speed Stall Speed Reference Stall Speed 1-g stall speed Mean Touchdown Speed Maximum Tire Speed Zero Fuel Weight Air density x

12 xi

13 1. Introduction The present work was developed in close collaboration with TAP Portugal, the national airline of Portugal. Operating almost 2,000 weekly flights through a route network that comprises 77 destinations in 34 countries worldwide, TAP is a large European airline. TAP currently serves a fleet of 55 Airbus aircraft, plus 16 that are operated by the regional subsidiary carrier PGA [2]. 1.1 Economic Scenario Just recently, in 2010, TAP has achieved a profit of roughly 62.3 million euros, an increase of 8.7% against the previous year, and this way a positive balance which had not happen since 2008 one of the worst years for the commercial aviation in history [3]. TAP is clearly a winner in the vast sea of airlines that nowadays struggle to remain afloat with only marginal profits. The global aviation industry has been living in a precarious balance between revenue and costs since the beginning of 2000, marked by the global economic slowdown and the terrorist attacks of 11 September 2001 [4]. At this time, global economy is in recession as a consequence of the increasing demand of resources by the emerging countries which unbalance the global markets. To make matters worse, crude prices have been rising and in the past few years have been higher than ever (Figure 1 (a)). Figure 1 - (a) - Jet Fuel costs in the US [5]; (b) Overall Airline Costs Mirroring Fuel Price Changes (1971 as Base Year 1 ) [6]. According to ATA (Air Transport Association of America), crude price is now the largest cost in airlines operation besides, as fuel prices increase flights become less profitable (Figure 1 (b)). Crude price has an inherent growing tendency, which associated with its high economic and political unpredictability makes business planning very difficult. When fuel prices rise rapidly, airlines have limited options to mitigate these costs: they either generate more revenue or decrease nonfuel expenses [7]. Consequently, optimization is the key to success in this new era, and optimization is exactly what the present work is about. 1 Overall Airline Cost Index not to be confused with Cost Index (CI) usually expressed in kg/min. 1

14 1.2 Relevance In commercial aviation, profit demands cargo and passengers, which in an engineer s point of view translates as weight. To maximize aircraft s weight at takeoff, aircraft performance optimizations must take place. Although takeoff and landing represent only a small portion of the total operation of an aircraft, performance of these two phases is considered very important due to entirely different reasons [8]. First, a great majority of accidents (mostly attributed to pilot error) occur during landing or take-off. Second, it is the take-off portion that establishes the engine sizing (in conjunction with air worthiness requirements) for design of civil aircraft. More importantly, civil airlines more than ever, need to optimize the weight of their aircraft to become more competitive. This way, it is not a surprise that takeoff and landing are the most strictly regulated segments of a flight [9, pp. 16-2]. For safety reasons, authorities such as the JAA (Joint Aviation Authority) and the FAA (Federal Aviation Administration) have laid down operational procedures to ensure a safe practice during the takeoff and landing stages. Performance data calculation and optimization reflect through the whole airline operation. Besides having flight safety as its ultimate concern, data availability and easy recalculation makes airline s operation more safeguarded to operation disruptions due to external agents. Also, the quality of this data reflects in the airline s balance sheets at the end of the year as the result of possible savings in different areas of operation [1]. 1.3 Airlines Operational Context Nowadays, airlines either subcontract or calculate takeoff performance by themselves. This data is presented in the form of tables such as the Regulatory TakeOff Weight (RTOW) and Regulatory Landing Weight (RLW) charts. Generally speaking, they consist in a list of weights (RTOW) and operational speeds as a function of specific parameters (such as aircraft model, runway characteristics and weather conditions). Besides providing utmost important data to airliner pilots, RTOW charts also provide important information for several ground operations, especially for the flight dispatcher who uses these documents during the planning and monitoring processes of aircraft s activities. In a similar way, to dispatch an aircraft, an operator has to verify landing requirements based on aircraft certification and on operational constraints defined in regulation, which is usually achieved by interpretation of RLW charts. 1.4 Objectives The present work focuses in the development of a new performance optimization application Takeoff and Landing Performance Program (TLP) intended for on ground use. It is intended to run under windows environment and was projected to be as user-friendly as possible. The resulting optimization output is presented in the form of runway takeoff weight and landing charts, which can be either printed or exported as PDF and Excel files, making TLP a dynamic and valuable tool for TAP s engineers. This project is borne alongside TAP s in-house project for an Electronic Flight Bag (EFB) an electronic system that displays a variety of aircraft data and executes performance calculations [10]. 2

15 1.5 Dissertation Structure The present work is split in 8 distinct chapters. The current chapter provides the conceptual goals and context for the developed work. TAP s Case Study can be understood as an extension of the present introduction; it intends to translate the actual state of RTOW chart creation, maintenance and usage at TAP Portugal and foresee how the present work will improve these processes. Chapters 3 and 0 provide the conceptual basis for chapter 5 - Takeoff Optimization. Landing Performance is addressed on chapter 6. Chapter 7 - Takeoff and Landing Performance Application (TLP) - describes the computational application that results from the present work. Finally, a conclusion is presented on chapter 8, together with final thoughts on the present topic. 3

16 2. TAP s Case Study In this section the author intends to understand the actual state of RTOW charts creation, maintenance and usage at TAP Portugal, identifying the operational needs and new ways to improve the current processes. Notice that the information in the following lines was retrieved directly from TAP s personnel. There are two main target groups at TAP Portugal that currently handle RTOW charts in their daily activities and that will benefit directly from the present work: the flight dispatchers and the flight operations engineering department. Pilots will also benefit from this software since they will be allowed to perform calculations for training purposes, outside their schedule flights. 2.1 Flight Dispatch The flight dispatcher is responsible for planning and monitoring the aircraft s activities. They receive the expected payload for each flight from Load Control and use TAP s flight plan calculation program to calculate the ICAO 2 flight plan which they must submit to EUROCONTROL. Also, the required fuel is also computed and an automated message is sent to the fuel suppliers. Simply put, he must check the weather conditions by consulting the newest Aviation Routine Weather Report (METAR) or Terminal Aerodrome Forecast (TAF), which he can retrieve through TAP s intranet system. Depending on the weather conditions he will know (or at least predict) which runway will be in operation at takeoff (headwind improves aircraft performance). Then, he must access TAP s RTOW chart repository and find the chart that matches the aircraft (for which he is planning the flight) and runway (that he identified by reading the weather conditions). However, it is a common practice to have several charts for the same aircraft and runway, each one corresponding to different conditions (such as different aircraft configurations, or different runway conditions or intersections). Many times this process requires the flight dispatcher to interpolate between different lines of the same chart (e.g. temperature value between two lines), or to perform additional performance calculations to contemplate conditions that are not present in any chart in the repository (e.g., slush on the runway). 2.2 Flight Operations Engineering Department The Flight Operations Engineering Department is without a doubt in need of a new and more dynamic aircraft performance calculation tool. One example of a task performed by TAP s engineers is the calculation of aircraft maximum payloads; currently, to accomplish this task the engineer needs to gather several data that is spread across the innumerous RTOW charts. First, he must identify which aircraft configuration results in a higher Maximum TakeOff Weight (MTOW) for the airport s reference temperature. Since each chart only displays information related to two of the possible configurations, he must handle different charts at the same time. Additionally, it may be necessary to perform interpolations since the airport reference temperature might not be strictly specified in those tables. The whole process can be extremely time-consuming and give way to possible 2 ICAO - International Civil Aviation Organization. 4

17 mistakes. Besides, since the current tables are stored as PDF files, the engineer may find himself copy-pasting the values from the charts to another work tool such as Microsoft Excel or Matlab. 2.3 Remarks Summing up, it would appear that in both cases the performance considerations can be very time-consuming. Also, when they demand delicate performance calculations, they leave room for human error. Furthermore, most times, hand-made performance optimizations tend to use more conservative approaches than the computational methods and consequently it is evident that there is room for optimization. Also, it seems that the engineers are lacking of a more dynamic tool, one that could, for instance, export optimization results as an Excel file so that the data could be handled without requiring to be manually processed. 5

18 3. Aircraft Performance The aim of this section is to provide the necessary background on aircraft performance for the following chapters of the current work. Aircraft operational limitations and configurable settings will be object of full attention Aircraft Settings Aircraft Configuration Modern aircraft take advantage of high-lift devices like slats and flaps (Figure 2) to change their wing shape and respective aerodynamic performance. Figure 2 - High-lift devices on an Airbus A340 (adapted from [11]). The main function of trailing edge flaps is to increase the camber (curvature) and the surface of the wing enabling it to produce more lift, at the expense of increased drag [9]. There are many different flap designs. The following picture represents a simple flap (a) and a fowler flap (b). The last one can be seen in the Airbus A340 for example [12]. Figure 3 Simple (a) and fowler (b) trailing edge flaps [9]. In opposition, the purpose of leading edge high-lift devices like slats (Figure 4) is not to increase the lift coefficient for a given angle of attack. Their aim is to delay airflow separation until a higher angle of attack is reached and this way helping the wing to achieve a higher maximum lift coefficient than would be otherwise possible [9]. 6

19 Figure 4- Slat [9]. Figure 5 - Flaps lever [13]. The pilot uses the flaps lever (Figure 5) to select simultaneously the slat and flap setting. Consequently, it is a common practice to refer to the flap setting and the aircraft configuration interchangeably. For that reason the author will make no distinction between these two terms. For example, considering an Airbus A320, the five positions of the flaps lever correspond to the following surfaces positions: Lever Position Slats Flaps Flight Phases Cruise / Hold Hold / Approach (14 ) Takeoff Approach (21 ) Approach / Landing Full (*) (25 ) Landing (*) : 40 for A320 with IAE 3 engine or A319 ( ) : setting for A321 Table 1 - A320 family Flap and Slat configurations [14]. Additionally, some aircraft configurations also activate the speedbrakes (e.g. configuration FULL or configuration 3 for A321 [14]) Engine Bleeds Aircraft engine bleeds are required by the Anti-Icing and the Air Conditioning systems. The following figure represents the Environmental Control System (ECS) schematic; its purpose is to highlight the connections between the engines, the Anti-Icing and the Air Conditioning systems (see ATA 21 refers to Air Conditioning ATA 26 refers to Pneumatic Systems Figure 6). From an aircraft performance engineer s perspective, operation of any of these systems degrades the performance of the aircraft since the engine air bleed for de-icing or air conditioning, implies a decrease in engine thrust [15, p. 124]. This reflects negatively on the climb gradients and consequently on the takeoff and landing performance. Although the air conditioning can be switched on or off (depending on the company policy), the anti-icing system must be switched on if the environmental conditions demand it (according to regulation). 3 International Aero Engines (engine manufacturer) 7

20 ATA 4 21 refers to Air Conditioning ATA 26 refers to Pneumatic Systems Figure 6 - Environmental Control Systems for the A320 family [14] Aircraft Status (MEL/CDL) Aircraft status is dealt with by the Minimum Equipment List (MEL) and the Configuration Deviation List (CDL). MEL procedures were developed to allow the continued operation of an aircraft with specific items of equipment inoperative under certain circumstances. The ( ) [FAA and the JAA have] found that for particular situations, an acceptable level of safety can be maintained with specific items of equipment inoperative for a limited period of time, until repairs can be made. The MEL document describes the limitations that apply when an operator wishes to conduct operations when certain items of equipment are inoperative [16]. Under certain conditions, aircraft may be approved for operations even with missing secondary airframe and engine parts [16]. The aircraft source document for such operations is the CDL. Since under these circumstances aircraft performance may be affected, considerations must be made for the takeoff and landing optimization processes. For this purpose, the developed computational method takes advantage of a CDL database (provided by the manufacturer) as will be explained in the 8 th chapter of the current work. In the aircraft s MEL/CDL manual items are addressed by their ATA code. Table 2 is an example of the CDL items referenced in the MEL/CDL manual, in this particular case, for an Airbus A Air Transport Association of America Spec 100 A broadly used specification that provides common reference for all commercial aircraft documentation. It defines a widely-used outline for aircraft parts and systems, according to their characteristics and functions which are referred as ATA Chapters [34]. 8

21 ATA Chapter ATA21 AIR CONDITIONING ATA27 FLIGHT CONTROLS ATA33 LIGHTS ATA52 DOORS ATA54 NACELLES/PYLONS ATA57 WINGS Items ATA21-01 Ram air inlet flap ATA21-01 Ram air inlet flap (MOD 26363) ATA21-02 Ram air outlet flap ATA27-01 Flaps track fairing ATA27-08 Seal between Inboard and Outlet flap ATA33-04 Upper 7LV and lower 6LV anti-collision (beacon) light cover ATA52-01 Toilet servicing door and drainage 172AR ATA52-02 Access door to hydraulic ground connectors. 197CB - 197EB - 198CB ATA52-04 Access door to opening control of landing gear doors on ground 195BB ATA52-08 Cargo door opening system - Access door of cargo opening system 134AR ATA52-09 Nose landing gear main doors (713, 714) ATA52-10 Nose landing gear aft doors (715, 716) ATA52-12 Main landing gear door (732, 742) (flight with gear up) ATA52-13 Main landing gear door (733, 743) (flight with gear up) ATA52-14 Main landing gear door (732, 742) (flight with gear down) ATA52-15 Main landing gear door (733, 743) (flight with gear down) ATA52-16 Main landing gear door (734, 744) (flight with gear down) ATA52-18 Main landing gear door: Seal on secondary hinged fairing ATA52-19 Pax door upper cover plate ATA52-22 Forward cargo door access cover panel 825AR ATA52-23 Aft cargo door access cover panel 826AR ATA54-01 Nacelle Strake ATA54-03 Pylon pressure relief door 413 (423)BL (424)BR ATA57-01 Wing tip fence - Complete wing tip fence ATA57-01 Wing tip fence - Lower part of wing tip fence Table 2 - A CDL (data from LPCAirport database) Aircraft Limitations Limiting Speeds This subchapter is not an enumeration of all the limiting speeds. Since its aim is to provide the reader with a background for the subsequent chapters, the author will focus on the most relevant definitions and the ones that have a direct impact on the takeoff and landing optimizations. a) Stall Speed Stall is a loss of lift caused by either the breakdown of airflow over the wing when the angle of attack passes a critical point, or at a fixed angle of attack, when the speed goes bellow a critical value. Air velocity increases over the wing with the angle of attack 5, it follows that air pressure decreases and consequently the lift coefficient increases. This can be seen across the blue section of the figure below: 5 The angle formed between the relative airflow and the chord line of the airfoil [30]. 9

22 Figure 7- CL versus angle of attack (adapted from [15]). The lift coefficient increases until it reaches the maximum lift point (C LMAX ). From this point on the lift coefficient suffers a sudden decrease. This occurrence is called a stall and two speeds can be identified [15]: V S1g, which corresponds to the maximum lift coefficient, when the load factor is equal to one. V S, which corresponds to the conventional stall, when the load factor is already less than one. V S1g is the reference stall speed for the airbus fly-by-wire aircraft and consequently for all the TAP s aircraft. Consequently, as in Airbus official documentation, in this work V S is referred to as V S1g. b) Minimum Control Speed on the Ground (V MCG ) The Minimum Control Speed on the Ground (V MCG ) defines the minimum speed that ensures that the aircraft will remain controllable during the takeoff roll, in the event of an engine failure on the ground [17]. According to regulations, the lateral excursion must be less than 30 feet after an engine failure on the ground (see Figure 8) (JAR (e)). Figure 8 - V MCG (adapted from [18]). 10

23 The following conditions are assumed for V MCG determination [18]: Most critical takeoff configuration Most unfavorable center of gravity Most unfavorable takeoff weight Aircraft trimmed for takeoff 6 Operating engines on takeoff power VMCG mainly depends on [15]: Engine(s) thrust and position Pressure altitude For further information on V MCG see Appendix A - JAR (e). c) Minimum Control Speed in the Air (V MCA ) Minimum Control Speed in the Air (V MCA ) is the speed at which in case of an engine failure the aircraft can be controlled either with a 5 degree maximum bank angle (Figure 9 a), or with zero yaw (Figure 9 b) (JAR (b) and (c)). Figure 9 - Sideslip angle (a) and bank angle (b) in a one-engine-inoperative condition (adapted from [17]). All the conditions for the determination of V MCG are assumed plus [18]: The aircraft is airborne and out of ground effect Landing gear is retracted Inoperative engine windmilling 7 Further information on VMCA is presented in Appendix A - JAR , paragraphs (b) and (c). 6 Trimmers adjusted in order to get the required hands-off pitch attitude prior to the takeoff [30]. 7 Turning around by wind force only, without engine power [30]. 11

24 d) Minimum Unstick Speed (V MU ) According to regulation, V MU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and continue the takeoff (JAR (d)). V MU is determined during low speed flight test demonstration (Figure 10). The control stick is pulled to the limit of the aerodynamic efficiency of the control surfaces, taking the aircraft on a slow rotation to an angle of attack at which either the maximum lift coefficient is achieved, or the tail strikes the runway (for geometrically limited aircraft) [15] (Figure 10). Figure 10 - V MU determination (adapted from [17] and [18]). Two minimum unstick speeds must be determined and validated during flight tests: all engines operatives (AEO) : V MU(AEO) with one engine inoperative (OEI) : V MU(OEI) In the one-engine inoperative case, V MU(OEI), sufficient lateral control must be ensured in order to prevent that an engine or a wing hits the ground [18]. It appears that [18]: (1) See Appendix A - JAR , paragraph (d) for additional details on V MU. e) Minimum Speed During Approach and Landing (V MCL ) V MCL is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aircraft with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5 (JAR (f)). The establishment condition for the V MCL may be consulted in the Appendix 1 - JAR , paragraph (f) and (h). For aircraft with three or more engines a minimum speed during approach and landing with a critical engine inoperative - V MCL(OEI) - is also determined. V MCL(OEI) establishment conditions are provided in Appendix A - JAR , paragraphs (g) and (h). f) Maximum Brake Energy Speed (V MBE ) Assuming that aircraft brakes absorb the whole kinetic energy in the form of heat, during braking, at higher speeds than V MBE the brakes become irreversibly damaged [15] [18]. 12

25 V MBE depends on [18]: Aircraft weight Meteorological conditions Runway slope g) Maximum Tire Speed (V TIRE ) V TIRE is the maximum ground speed specified in order to limit the centrifugal forces and heat that may damage the tire structure. This speed is specified by the tire manufacturer [18]. For most Airbus aircraft models, V TIRE = 195 knots [15] Structural Weights The total weight of an aircraft is usually split as illustrated in the following figure: Figure 11 - Aircraft Weights [15]. MEW, or Manufacturer s Empty Weight, is the weight of the structure, power plant, furnishings, systems and other items of equipment that are considered an integral part of the aircraft. It is essentially a dry weight, including only those fluids contained in closed systems, [15, p. 42]. OEW stands for Operational Empty Weight, which is the Manufacturer s Empty Weight plus the operators items such as the flight and cabin crew and their luggage, documents, seats and fluids (e.g. unusable fuel, engine oil, toilet) [19]. DOW or Dry Operating Weight is the total weight of the aircraft when it is ready for a specific type of operation, excluding all usable fuel and traffic load (JAR-OPS (a)). 13

26 ZFW, or Zero Fuel Weight, is the Dry Operating Weight plus the traffic load (passengers, passenger s bags and cargo) [19]. ZFW = DOW + traffic load TOW or Takeoff Weight is the aircraft weight at the start of the takeoff run. It equals the Zero Fuel Weight plus the fuel at brake release point or the Landing Weight plus the trip fuel ( the weight of the fuel required to cover the normal leg without reserves, [15] [19]: TOW = DOW + traffic load + fuel reserve + trip fuel LW stands for Landing Weight, which is the weight of the aircraft at the moment of landing at the destination airport. It is equal to Zero Fuel Weight plus the fuel reserve [15]: LW = DOW + traffic load + fuel reserve Maximum Structural Weights As stated in JAR 25.25, aircraft maximum weights must never exceed the highest weight selected by the applicant for the particular conditions, neither the highest weight at which compliance with each applicable structural loading and flight requirement is shown (see Appendix A - JAR for more detailed information). Taking this into account, the Maximum Structural is the maximum permissible total aircraft weight at the start of the take-off run (JAR-OPS (d)) and consequently TOW must never exceed this value. In the other hand, the Maximum Structural Landing Weight represents the maximum permissible total aircraft weight at the moment of landing (JAR-OPS (c)) Environmental Envelope The environmental envelope (see Figure 12) consists in the operational limits for the ambient air temperature and operating altitude (pressure altitude). Inside this envelope, aircraft performance has been fully defined and its respective systems have met certification requirements [15]. The green area in Figure 12 denotes the takeoff and landing operational limits. Figure 12 - A Environmental Envelope (adapted from [20]). 14

27 Engine Limitations The main cause of engine limitations is due to the Exhaust Gas Temperature (EGT) limit, [15, p. 44]. The following table illustrates a typical example of EGT limits, in this case for an A aircraft: Operating Condition Time Limit EGT Limit Note 5 min TOGA 950 C 10 min Only in case of engine failure MCT Unlimited 915 C CL Unlimited 915 C Starting 725 C Table 3 - Thrust Setting and EGT Limit for an A (CFM56-5C3 engine) [21]. TOGA stands for Takeoff-Go-Around [22]. The Takeoff and Go-Around thrust represents the maximum thrust available for takeoff and go-around sequences; it is certified for a maximum of 5 minutes (or 10 minutes if an engine failure occurs). MCT, or Maximum Continuous Thrust [22], is the maximum thrust that can be applied unlimitedly during a flight. It must be selected in case of engine failure, when TOGA thrust is no longer allowed due to time limitation, [15, p. 42]. CL stands for Climb [22] and represents the maximum thrust available during the climb phase. Notwithstanding its relevance, EGT is not the only limitations to take into account during aircraft operation. Aircraft s engines perform differently according to the current Outside Air Temperature (OAT) and pressure altitude. These performance variations must be taken into account. As a general rule, at a given pressure altitude, the available thrust decreases with temperature past a certain value of temperature - the reference temperature (T REF ). On the other hand, at a given temperature, any increase in the pressure altitude leads to decreasing the available takeoff thrust. The following figure illustrates the engine thrust variation according to both these factors: Figure 13 - TOGA thrust versus OAT and PA for a given engine type [15]. 15

28 4. Takeoff Performance In the present chapter the author introduces the agents that condition the takeoff performance, and that will in some way limit it. First, the runway distances and specifications are presented, followed by the surrounding obstacles and resulting flight path limitations. Then the outside elements and their influence will be described, such as the weather and the runway conditions. Finally all the resulting limitations will be summarized in a diagram to provide a better overall comprehension. The takeoff sequence can be split in three major phases as illustrated in the following figure: Figure 14 - Takeoff Profile [15]. During the takeoff phase, the aircraft must achieve sufficient speed and angle of attack in order to develop sufficient lift (L) to overcome its weight (mg): In which: (2) Air density (fixed) S Aerodynamic reference wing area (fixed) V Airspeed Lift coefficient (increases with angle of attack) 4.1. Operational Speeds a) Engine Failure Speed (V EF ) Due to regulations, the most critical engine 8 failure must always be taken into account to ensure a safe takeoff. V EF is the calibrated airspeed at which the critical engine is assumed to fail. V EF may not be less than V MCG (JAR (a)). b) Decision Speed (V 1 ) For every single takeoff, there are three critically important speeds that the pilot must observe carefully, V 1, V R and V 2 [9]. According to regulation, V 1, in terms of calibrated airspeed, is the take-off decision speed (see Appendix A JAR , paragraph (a) for further regulatory description). In JAR Part 1, V 1 is defined as the maximum speed in the takeoff at which the pilot must take the first action (e.g. apply brakes, reduce thrust, deploy speed brakes) in order to stop the airplane within the limits of the runway. 8 Critical Engine means the engine whose failure would most adversely affect the performance or handling qualities of an aircraft, i.e. an outer engine on a four engine aircraft (JAR 1.1). 16

29 V 1 can be selected by the applicant, assuming that an engine failure has occurred at VEF (JAR (a)). Since even the best pilots have some time delay between making a decision to reject the takeoff and actually initiate the rejected takeoff (RTO) procedure (by first applying the wheel brake) [9], the resulting reaction time ( ) must be taken into account: Figure 15 - Decision Speed [15]. Consequently, V 1 corresponds to the V EF speed plus one second of acceleration with one engine inoperative [9] [15]: Additionally, V 1 must be less than or equal to V MBE or V R, whichever is less [9]: (3) { (4) It follows that sometimes V 1 does not have a unique solution, corresponding instead to a range of valid values. In a similar way to other airlines, TAP defines V 1 as the lower bound of that possible range which is the most conservative value: a lower V 1 grants the pilot with more time to execute the RTO procedure. c) Rotation Speed (V R ) V R is the calibrated airspeed at which the pilot initiates the rotation sequence by, pulling back on the control column, raising the nose of the aircraft to its takeoff attitude [9]. According to regulation, V R must be less than V 1 and 105% of V MCA (JAR (e)): This speed has critical implications for takeoff safety, because it directly affects the liftoff speed, V LOF and the initial takeoff climb speed V 2 as well as the takeoff distance [9]. For further regulatory information on V R see Appendix A JAR (e). (5) d) Lift-off Speed (V LOF ) V LOF is the calibrated airspeed at which the aircraft lifts off the ground [18]. In order to ensure good flight handling qualities at lift off, the authorities placed two constraints on V LOF : 17

30 These conditions are for geometrically limited aircraft such as the A319, A320, A321, A330 and A340 (all of TAP s fleet), for more detailed regulatory information see Appendix 1 JAR (e). Additionally, the lift off speed, in terms of grounds speed, must not exceed the maximum tire speed [18]. e) Takeoff Climb Speed (V 2 ) V2 is the minimum calibrated airspeed that must be reached at a height of 35 feet above the runway surface, assuming the event of an engine failure [15]. 35 feet is the value used for the usual dry runway situation; for non-dry runway conditions, and for the engine-inoperative takeoff case only, this height is reduced to 15 feet [9]. The regulations place the following requirements on V 2 (JAR (b) and (c)): (6.1) (6.2) (7.1) (Fly-By-Wire aircraft) (7.2) (other aircraft) (7.3) As the whole TAP fleet is composed by Fly-By-Wire 9 (FBW) aircraft, the author will consider from this point on that V 2 must be at least 1.13 times the V S1g. For further reading on this topic, see Appendix A JAR , paragraphs (b) and (c). f) Speed Summary The following figure illustrates the relationships and the regulatory margins between the certified speeds seen in chapter 5 (V S1g, V MCG, V MCA, V MU, V MBE, V TIRE ) and the takeoff operating speeds (V 1, V R, V LOF, V 2 ). Figure 16 - Takeoff Speed Summary and Limitations related to V 1, V R, V LOF and V 2 [15]. 9 Fly-By-Wire is a kind of technology which interprets movements of the pilot s controls and, with the aid of computerized electronics, moves the control surfaces accordingly [30]. 18

31 4.2. Runway The runway is a rigid or flexible rectangular area, on concrete or asphalt, used for takeoff and landing. In addition to the runway (RWY), there are two regions that must be considered when accounting for the available takeoff lengths: the stopway (SWY) and the clearway (CWY). Notice that although these areas contribute to a better aircraft performance, they are not mandatory, so they may not be present in every runway. The Stopway is a rectangular area beyond the takeoff runway designated by the airport authorities for use in decelerating the aircraft in case of a RTO [18]. Figure 17 - Stopway (adapted from [15]). In a similar way, the clearway (CWY see Figure 18) is also a rectangular area beyond the runway, located on the same centerline and under control of the airport authorities [18]. Its main purpose is to provide a clear takeoff path (without obstacles). Figure 18 - Clearway (adapted from [15]) Available Takeoff Lengths (TORA, ASDA and TODA) There are three major takeoff lengths that must be well known prior to any takeoff performance evaluation on any runway: the Takeoff Run Available (TORA), the Accelerate Stop Distance Available (ASDA) and the Takeoff Distance Available (TODA). TORA is either equal to the runway length, or to the distance from the runway entry point (intersecting taxiway) to the end of the runway (JAR-OPS 1.480). ASDA is the runway length available for acceleration and subsequent deceleration, including the stopway, if any [18]. In other words, it is the TORA plus the stopway. As for TODA, it is the length of the take-off run available plus the length of the clearway available (JAR-OPS 1.480). 19

32 Figure 19 summarizes these three definitions. Figure 19 - Available Takeoff Lengths (adapted from [15]) Lineup Adjustments Airplanes typically enter the takeoff runway from an intersecting taxiway. When this intersection has a high degree angle (e.g. 90, 180 ) the previous distances (ASDA and TODA) must be corrected. In other words, a lineup adjustment must be considered (see Figure 20 and Figure 21). Figure 20 - Lineup Adjustment, Top (adapted from [15]). Figure 21 - Lineup Adjustment, Side 10 (adapted from [15]). 10 Notice that in this particular situation the runway does not have a clearway. Consequently, if there were no lineup adjustments: ASDA = TODA. 20

33 In this particular case, for a 90 entry type, the following values apply: Aircraft Model ASDA Correction TODA Correction A ft 42 ft A330-3XX 158 ft 74 ft A340-3XX 169 ft 85 ft Table 4 - Lineup Adjustments for 90 Runway Entry [18] Takeoff Lengths a) Takeoff Distance (TOD) According to regulation (see Appendix A, JAR for a more complete description), assuming a set of operational conditions (outside air temperature, pressure, weight, etc.), the takeoff distance on a dry runway is given by [15]: { } (8.1) In a similar way, on a wet runway the takeoff distance is given by [15]: { } (8.2) Naturally, the takeoff distance must be less than the available takeoff distance: (9) b) Takeoff Run (TOR) Like in the TOD determination, on a dry runway the takeoff run is given by [15] (see Appendix A JAR for further regulatory information): On a wet runway, however, it is a slightly different [15]: It follows: { } (10.1) { } (10.2) (11) c) Accelerate-Stop Distance (ASD) The accelerate-stop distance on a dry runway is the greater of the following values [15] (see Appendix A JAR for supplementary information): { } (12.1) As for the wet runway situation, it is the greatest of the following three values [15]: Naturally: { } (12.2) (13) 21

34 Runway Slope Airbus aircraft are all basically certified for takeoff on runways whose slopes are between -2% and +2% [15, p. 77]. A positive slope increases the takeoff distances and reduces the accelerate-stop distances, a negative slope results in the opposite: Figure 22 - Runway slope effect on takeoff performance [15] Obstacles and Takeoff Trajectory In order to account for the surrounding obstacles and climb gradients restrictions, the takeoff trajectory must be subject of analysis Takeoff Flight Path As seen before, the aircraft is accelerated on the ground to V EF, at which point the critical engine is considered inoperative, remaining this way for the rest of the takeoff. Also, V 2 speed must be reached before the aircraft reaches 35 ft above the ground. This is the transition point to the first segment of the takeoff flight path which will last to a point at which the aircraft is at a height of 1500 ft above the takeoff surface, or at which the transition from the takeoff to the enroute configuration is completed and the final takeoff speed is reached (JAR ). It is standard industry practice to split the takeoff flight path into four segments. These are distinctly separated pieces of the profile, each characterized by a different configuration or thrust settings [9]. Figure 23 and Table 5 provide a good description of the takeoff flight path and its respective segments. Notice that according to TAP s policy the minimum level-off height (gross height at the third segment) must me at least 1500 ft (instead of 400ft). Also, the minimum height of the transition point from the final segment to climb is 3500 ft (instead of 1500 ft). These are, of course, more conservative definitions. 22

35 Figure 23 - Takeoff Path and Definition of Various Segments [15]. Minimum Climb Gradient (OEI) Start When Slats/Flaps Configuration First Segment Second Segment Third Segment Final Segment Twin 0.0% 2.4% - 1.2% Quad 0.5% 3.0% - 1.7% V LOF reached Takeoff Gear retracted Takeoff Acceleration height is reached Slats/Flaps retraction En route configuration achieved Clean Engine Rating TOGA/FLEX 11 TOGA/FLEX TOGA/FLEX MCT Speed Reference V LOF V 2 Acceleration from V 2 to Green Dot 12 Green Dot Landing Gear Retraction Retracted Retracted Retracted Ground Effect Without Without Without Without Table 5 - Takeoff Segments Characteristics (adapted from [15]). 11 Flexible takeoff is explained in chapter Green Dot speed is the optimum climb gradient speed, one engine out (APT INT A ) 23

36 Obstacle Clearance Most of the time, runways have surrounding obstacles that must be taken into account prior to takeoff, to determine that the aircraft is able to clear them with a certain safety margin. This leads to the definition of gross and net flight paths. Also, Some airports are located in an environment of penalizing obstacles, which may necessitate turning to follow a specific departure procedure [15, p. 65]. Turning departures are subject to specific conditions. a) Gross and Net Flight Paths The gross flight path is the takeoff flight path actually flown by the aircraft (JAR (a)), while the net flight path is the gross takeoff flight path minus a mandatory reduction (JAR (b)). This mandatory reduction, based on a climb gradient reduction, must grant a safety margin of 35 ft between the aircraft and every obstacle in its flight path (see Figure 24). Two engine aircraft have a gradient penalty of 0.8%, while four engine aircraft have their takeoff path reduced at each point by a gradient equal to 1.0% (JAR (b)). Figure 24 - Gross and net takeoff paths [15]. b) Takeoff Turn Procedure According to regulation, no track changes are allowed before the aircraft achieves a height equal to one half its wingspan (Table 6) and before reaching at least 50 ft above the end of TORA. Aircraft Type Wingspan Minimum height to start a track change A319/A320/A m (111 ft 10 in) 56 ft A / m (197 ft 10 in) 99 ft A / m (197 ft 10 in) 99 ft Table 6 - Minimum height to start a track change according to wingspan [18]. 24

37 Also, no bank angle should exceed 15 under a 400 ft height. Above 400 ft, bank angles must be under 25. If at any time the banking angle gets over 15, then the whole net flight path must clear all obstacles by at least 50 ft (JAR-OPS (c)). Greater banking angles, other than the ones specified, may be applied but are subject to specific approval by the Authority (JAR-OPS (c)) Departure Sector The departure sector delimits an area surrounding the takeoff flight path, within which all obstacles must be cleared, assuming they are all projected on the intended track [15, p. 71]. The following figures represent departure sectors with and without heading changes over 15. Figure 25 - Departure Sector for track changes under 15 [15]. Figure 26 - Departure Sector for track changes over 15 [15]. E stands for the width of the departure sector, which must be equal to 90 m plus x D or 60 m plus x D, for aircraft with a wingspan of less than 60m. D is the horizontal distance the aircraft has traveled from the end of the take-off distance available or the end of the take-off distance if a turn is scheduled before the end of the take-off (JAR-OPS (a)). 25

38 The following table represents the semi-width (1/2E 0 ) at the start of the departure sector for TAP s aircraft: Aircraft Type Wingspan 1/2E 0 A319/A320/A m (111 ft 10 in) 56 ft A / m (197 ft 10 in) 99 ft A / m (197 ft 10 in) 99 ft Table 7 - Semi-width ( E 0) at the Start of the Departure Sector [18]. In the situation where there are no heading changes over 15, the maximum width of the departure sector is 300 m if the pilot is able to maintain the required navigational accuracy and 600 m otherwise (JAR-OPS (d)). When the aircraft performs track changes above 15 these values increase to 600 and 900 m, respectively (JAR-OPS (e)) Outside Elements Considerations must be made to account for the external conditions of the day which can vary considerably on a daily basis Wind For performance purposes, only the wind component that is parallel to the runway (headwind HW) is considered (Figure 27). The crosswind component can be safely overlooked in the takeoff optimization because it has a negligible effect on the aircraft acceleration [9]. Figure 27 - Headwind determination. The headwind component has a positive effect on takeoff performance by shortening the takeoff distances (the ground speed is reduced - see Figure 28). In the presence of tailwind the opposite occurs, the takeoff performance degrades and the resulting takeoff distances increase. 26

39 Figure 28 - Headwind effect on ground speed [15]. According to regulation, takeoff performance calculations must only consider 50% of the actual headwind component, or 150% of the actual tailwind component (JAR-OPS (c)). Notice that usually the takeoff software applications perform the 50% 150% corrections internally, so the wind input is simply the headwind or the tailwind, respectively. This is, of course, the case with TLP as well Pressure Altitude As was seen before, in chapter 3, engine performance degrades with pressure altitude: engine thrust decreases so the takeoff distances increase and the climb gradients decreases. Additionally, when the pressure altitude increases, the corresponding static pressure (P S ) and air density decreases (eq. 14 adapted from [23]) [15]. Consequently the pressure altitude also has a direct impact on aerodynamics (eq. 15). (14) (15) To compensate for a decrease in the air density, the true airspeed (TAS) of the aircraft must be increased and therefore the takeoff distance is also increased [15]. Summing up: Figure 29 - Pressure altitude effect on takeoff performance [15] Outside Air Temperature When the outside air temperature (OAT) increases the air density ( ) decreases (see eq. 14). Consequently the takeoff performance degrades in a similar way as with the pressure altitude: TAS must increase, therefore the takeoff distances increase as well (see Figure 29). 27

40 Runway Condition The runway condition is utmost important when accounting for the takeoff (and landing) performance. The runway is, after all, the surface between the aircraft and the ground. Therefore its state, or condition, defines the interaction between the two and, consequently, can take major impact in the aircraft acceleration or stopping capabilities, when compared to a dry runway. Since this is a topic of great complexity, this subsection can be seen as only a summary of the major considerations to take into account when evaluating the takeoff performance in a wet or contaminated runway. For an overall description of the physical processes and regulatory limitations that lead to the considerations in this sub-chapter see Appendix B Performance on Non-Dry Runways. When it comes to runway condition, the takeoff performance will depend on the depth and type of contaminant: Contaminant Wet Contaminated Water (fluid) < 3 mm 3 13 mm (1/2 ) Slush (fluid) < 2 mm 2 13 mm (1/2 ) Wet Snow (fluid) < 4 mm 4 25 mm (1 ) Dry Snow (fluid) < 15 mm mm (2 ) Compacted Snow (hard) - all Ice (hard) - all Table 8 - Wet and contaminated runways [15]. Contaminants can be divided into hard and fluid contaminants, which have a different effect on aircraft performance [15] Hard contaminants reduce friction forces; Fluid contaminants reduce friction forces, cause precipitation drag and aquaplaning. Also, as seen in the Table 8, the runway is considered either wet or contaminated, depending on the type and depth of the contaminant. This way, the performance software will consider the specific physical processes (friction forces, aquaplaning and drags) that apply for each kind of contaminant, as it will account for the particular regulations that apply for the corresponding runway state (wet or contaminated), which may also differ from the dry runway condition. When considering an all engines operating takeoff TOD, TOR and ASD are determined the same way as described early in this chapter, whatever the runway condition. When accounting for a one engine inoperative takeoff, however, TOD and TOR are calculated in a different way [18]: the use of reverse thrust credit is allowed for ASD determination; the gross flight path starts at 15 feet Limitation Summary All in all, the takeoff limitations, resulting from the the former definitions and regulatory constraints that were presented throughout this chapter can be summarized the following way (Figure 30 and Table 9): 28

41 Figure 30 - Takeoff Performance Limitations. The following table enumerates the resulting limitations: Code Limitation 1 1 st Segment 2 2 nd Segment 3 Runway 4 Obstacle 5 Tire Speed 6 Brake Energy 7 Maximum Weight 8 Final Takeoff V MU V MCG V MCA V 1 /V R Acceleration 3 rd Segment Gross Level-off Height Turn Height Table 9 - TAP s takeoff limitations. The first nine correspond to the original limitations set by Airbus official documentation, while the remaining five are in agreement with the new TAP s takeoff performance limitations table (currently implemented in TAP s EFB project). 29

42 5. Takeoff Optimization This section covers the principle/methodology used to optimize the takeoff performance. The optimization objective is to obtain the highest possible performance-limited takeoff weight Maximum Takeoff Weight (MTOW), while fulfilling all the airworthiness requirements seen in the past sections [15] and, consequently, respecting all the limitations enumerated in the past Table 9 - TAP s takeoff limitations. It is necessary to determine which parameters influencing the takeoff (influencing the limitations) are fixed Sustained Parameters (cannot be changed) and which offer freedom of choice Free Parameters. For instance, the current wind condition cannot be changed or chosen this is a sustained parameter. The influencing parameters are enumerated in the table below. Sustained Parameters Runway Outside Elements TORA TODA ASDA Lineup Adjustments Slope Condition Wind Pressure Outside Air Temperature Obstacles and Takeoff Trajectory Anti-Ice Aircraft Status (MEL/CDL) Free Parameters Flaps Setting Air Conditioning V1/VR Ratio V2/VS Ratio Table 10 - Influencing Parameters (adapted from [15] and [18]). As seen in the Aircraft Performance chapter, both the chosen flap setting and the engine bleeds condition take major impact in the aircraft performance, and consequently in the takeoff performance. Nevertheless the takeoff speeds represent the most important source of optimization and MTOW gain [15] [24]. This way, at a given configuration (and all sustained parameters), takeoff weight limitations are set as functions of V 1 /V R and V 2 /V S [18] Optimization Range Assuming a given aircraft condition, the takeoff optimization process will take place inside a well delimited range defined by the maximum and minimum allowed values for both speed ratios. a) V 1 /V R Range As mentioned in chapter 3, the decision speed, V 1, must always be less than the rotation speed, V R. Although V R depends on the weight and the value of V 1 is not fixed, the maximum V 1 /V R ratio is equal to one (V 1 /V R 1) [15]. 30

43 Also, the minimum V 1 /V R ratio is equal to 0.84 (manufacturer value [15]). This way, one can say that the V 1 /V R ratio has a well-defined range: This proves to be particularly useful since it also grants a well-defined range for the takeoff optimization process. Any V 1 /V R increase (resp. decrease) should be considered to have the same effect on takeoff performance as a V1 increase (resp. decrease) [15, p. 193]. (16) b) V 2 /V S Range As seen in chapter 6, the minimum value for V 2 imposed for Airbus Fly-By-Wire aircraft (all of TAP s fleet) is 1.13V S1g. Although V 2 does not have a fixed value (since the stall speed depends on the aircraft weight), the V 2 /V S ratio is known for a given aircraft type. This way, having a well-known range, the V 2 /V S ratio proves to be very helpful for the takeoff optimization process: A maximum value for V 2 (and consequently, a maximum V 2 /V S ) is specified by the manufacturer (see table below), which corresponds to an optimal V 2. Aircraft Family V2/VS range A V2/VS 1.35 A V2/VS 1.40 A V2/VS 1.45 Table 11 - V 2/V S maximum values for the Airbus family (data retrieved from [15]). Any V 2 /V S increase (resp. decrease) should be considered to have the same effect on takeoff performance as a V 2 increase (resp. decrease) [15, p. 194]. (17) 5.2. Free Parameters Influence This is one of the most significant sections of the present work since it will allow the reader to understand in detail the variables of the takeoff optimization and this way get a clear picture of how the weight optimization is actually performed. a) Flaps Setting Currently all of TAP s aircraft have three distinct sets of flaps and slats configurations that are specially designed for the takeoff procedure: Configuration 1+F, Configuration 2 and Configuration 3 [14]. Each of these configurations is associated with a set of certified performance, making it suitable for one specific situation but inappropriate for another (e.g. shorter/longer runway). On account of this, the optimum configuration is the one that provides the highest MTOW [15]. As a general rule, this is the chosen configuration. However there are some exceptions, take for example situations that may result in a loss of comfort by the passengers or that are prone to a tail strike event (e.g. using Configuration 1+F on extensive runways for long aircraft as the A340) [24] [20]). 31

44 The takeoff configuration selection also affects the FLEX temperature and consequently the level of necessary thrust [24]. This will be the focus of attention at the end of the current chapter. As a general rule, Configuration 1+F offers better aircraft performance on long runways (better climb gradients), whereas Configuration 3 provides better performance on short runways (smaller takeoff distances). Sometimes, other parameters, such as obstacles, can interfere. In this case, a compromise between climb and runway performance is required, making Configuration 2 the optimum configuration during takeoff [15]. The resulting takeoff distances and gradients achieved by the different configurations are illustrated in the subsequent figure: Figure 31 - Takeoff configurations performance (adapted form [15]). b) Air Conditioning Having the air conditioning switched on during takeoff results in a loss of power and consequently degrades the takeoff performance. c) V 1 /V R Ratio As the purpose of this sub-section is to analyze the impact of V 1 /V R ratio variation on the aircraft weight limitations, the V 2 /V S ratio will be considered a fixed parameter. Figure 32 translates the influence of the V 1 /V R ratio on the MTOW, limited by the runway limitations. Figure 32 - Runway Limited MTOW (adapted from [15]). A higher V 1 /V R ratio (or a higher V 1 ) leads to a higher percentage of the acceleration phase with all engines operating (remember that despite the value that V 1 will take, the engine failure is 32

45 assumed one second before it is achieved), consequently, it will take less time (and distance) to achieve V 2 at 35 ft. This translates in less restrictive TOD OEI and TOR OEI limitations. On the contrary, TOD AEO and TOR AEO are independent of V 1 as there is no engine failure, and thus no consequence on the acceleration phase and the necessary distance to reach 35 ft. As for the ASD, it will grow more limiting as V 1 increases, since a longer part of the runway is covered during both the acceleration and the braking phases [15]. Figure 33-a translates the influence of V1 on the climb and obstacle limited MTOW, while Figure 33-b shows its effect on the tire speed and brake energy weight limitations. Figure 33 Effect of V 2/V S in the (a) obstacles, takeoff segments, (b) brake energy and tire speed limitations (adapted from [15]). The V 1 speed has no direct influence on climb gradients and consequently on the 1 st, 2 nd and final segment gradients. However, as the takeoff distance is reduced (for higher values of V 1 ), the obstacle-limited weights are improved since the aircraft requires a lower gradient to clear the obstacles [15]. A maximum V 1 speed, limited by brake energy (V MBE ), exists for each TOW, this is why it seems to grow more limiting as V 1 increases. To achieve a higher V 1 speed, it is necessary to reduce TOW [15]. V 1 has no influence on the tire speed limitation. Taking into account the preceding limitations it is possible to find the optimal V 1 /V R which corresponds to the MTOW for a specific V 2 /V S ratio: Figure 34- Optimum V 1/V R [15]. 33

46 d) V 2 /V S Ratio In a similar way to the previous sub-section, the V 1 /V R ratio will now be considered as a fixed parameter this way allowing to study the influence of the V 2 /V S ratio on the MTOW limitations. As a general rule, for a given V 1 /V R ratio, any increase in the V 2 /V S ratio translates as an increase of the takeoff distance (both all-engine-operating and one-engine-out). This reflects the need to acquire more energy (speed) on the runway in order to achieve a higher V 2 speed at 35 feet. Consequently the acceleration phase is longer and the 2 nd segment slope increases [15]. Although the V 2 /V S ratio does not influence directly the ASD, a higher ratio leads to an increase in V R which demands a higher V 1 (for a given V 1 /V R ) and outcomes in a higher ASD. The resulting increase in V 1 translates as a reduction of the weight by the brake energy and tire speed limitations (see Figure 33-b) [15]. Additionally, any V 2 /V S increase results in higher climb gradients and consequently in less restrictive 1 st and 2 nd segment gradient limitations. It does not influence, however, the final takeoff gradient since this is flown at green dot speed. V 2 does not have a direct impact on the brake energy limitation. Nevertheless any increase in V 2 demands an increase in V 1, and consequently on V R as well (assuming a fixed V 1 /V R ratio) which results in a more restrictive brake energy limitation. Table 12 summarizes all the previous conclusions on the influence of V 2 /V R in the MTOW limitations. (Assuming a fixed V 1 /V R ) When V 2 /V S Increases Limitation Length/Clearance/Climb gradient/speed/energy Weight limited by ASDA TORA/TODA Close Obstacle Distant Obstacle 1 st Segment Gradient 2 nd Segment Gradient Final Segment Gradient - - Tire Speed Brake Energy - Table 12 - Influence of V 2/V S ratio on takeoff limitations [25] Optimization Process The Regulatory Take-Off Weight and associated takeoff speeds (...) are determined through an iterative process which looks for the optimum V1/VR for a given V2/VS and then for the optimum V2/VS for that V1/VR [25]. The process continues until the difference between two subsequent iterations is less than, or equal to, the specified precision. The following figure shows a spatial representation of the variation of MTOW with both speed ratios, for a given set of sustained parameters and aircraft configuration: 34

47 Figure 35- MTOW as function of V 1/V R and V 2/V S [25]. It is possible that under certain conditions the optimization results in a range of optimum solutions, instead of a single maximum: Figure 36 Range of soultions that maximize MTOW (adapted from [25]). Once the optimum speed ratios (V 1 /V R and V 2 /V S ) are obtained, the takeoff speeds are obtained as follows: Figure 37 - Takeoff speeds calculation [26]. AFM means that the information is obtained from the Aircraft Flight Manual (AFM). 35

48 5.4. Flexible Takeoff Although flexible temperature calculation is beyond the scope of the current work since it can only occur moments before an aircraft takes-off, there are some flex related parameters that should be provided in the RTOW chart such as the maximum flexible temperature (T Flex Max ) and the reference temperature (T REF ). This sub-chapter describes the maximum flexible temperature while introducing the concept and relevance of the flexible takeoff. A takeoff at reduced thrust is called a flexible takeoff, and the corresponding thrust is called flexible thrust [15, p. 87]. When the actual takeoff weight (ATOW) is lower than MTOW, takeoff may be performed with less than the maximum takeoff thrust (TOGA) (see Appendix A (c) for more regulatory information) [18]. Recalling that engine thrust drops when OAT increases, if ATOW is less than MTOW it is possible to determine the temperature at which the needed thrust would be the maximum thrust for this temperature see Figure 37. This temperature is called flexible temperature (T Flex ) or assumed temperature [15, p. 87]. Figure 38 - Flexible temperature principle [15]. Consequently, the flexible temperature is the input parameter through which the engine monitoring computer adapts the thrust to the actual takeoff weight. This method is derived from the approved maximum takeoff thrust rating, and thus uses the same certified minimum control speeds [15, p. 88], consequently complete aircraft performance data is available. Not only the thrust reduction may never be more than 25% below the maximum takeoff thrust, but also must be assured that TOGA speed may be applied at any time (AMJ (a)). Therefore, a flexible takeoff may only be performed when the following conditions are respected: Additionally, flexible takeoffs are not allowed on contaminated runways and should not be performed when wind shear is expected [24]. They may, however, be performed on wet runways when the required performance information is provided (Airbus operational (18) (19) (20) 36

49 documentation including the RTOW and FCOM see Appendix A1 AMJ 25-13, paragraph (f)). Takeoff at reduced thrust is only allowed with any inoperative item affecting the performance, if the associated performance shortfall has been applied to meet all performance requirements at the takeoff weight, with the operating engines at the thrust available for the flex temperature [21]. Performing the thrust reduction resulting from a flexible takeoff will save engine life [27], reduce maintenance costs and improve engine reliability [18] [24]. As a result it improves both safety and reduces operational costs. 37

50 6. Landing Performance To dispatch an aircraft, an operator has to verify landing requirements based on aircraft certification (JAR 25) and on operational constraints defined in JAR-OPS [15]. In normal conditions, these requirements are not very restrictive and most times aircraft are dispatched at their maximum structural landing weight (MLW). This leads to a minimization of importance of landing checks during dispatch. However, landing performance can be drastically affected when considering missing and/or inoperative aircraft items, under adverse external conditions and in the presence of a contaminated runway. This way, landing performance checks are of utmost importance and should always be taken into consideration to ensure a safe flight Operational Speeds a) Lowest Selectable Speed (V LS ) As a general rule, during landing, pilots have to maintain a stabilized approach with a calibrated airspeed of no less than V LS down to a height of 50 feet above the destination airport. V LS is defined as 1.23 V s1g of the actual configuration (for fly-by-wire aircraft) [15]: b) Final Approach Speed (V FA ) The final approach speed, or V FA, is the aircraft speed during landing, 50 feet above the runway surface. The flaps/slats are in landing configuration, and the landing gears are extended. V FA is defined as [28]: V LS for manual landing; V LS + 5 kt for CAT II/CAT III automatic landing 13. (21) c) Reference Speed (V REF ) This speed is used as reference for emergency in flight performance computations when a certain abnormality, or system failure, is verified. V REF means the steady landing approach speed at the 50 feet point for a configuration Full approach (reference configuration). Consequently: In case of a system failure affecting the landing performance, Airbus operational documentation indicates the correction to be applied to V REF to take into account the failure: (22) (23) 13 Auto-thrust is used or to compensate for ice accretion on the wings [15]. 38

51 6.2. Runway Landing Distance Available (LDA) When no obstacle exists under the landing path the landing distance available is equal to TORA [15], otherwise this distance must be shortened by defining a threshold considering a 2% tangential to the most penalizing obstacle plus a 60 m margin (Figure 39). Figure 39 - Obstacle influence on LDA [15]. In this case, the Landing Distance Available (LDA) is equal to the length measured from the displaced threshold to the end of the runway. This value is specified for each runway Actual Landing Distance (ALD) a) Manual Landing The actual landing distance is the distance measured between a point 50 ft above the runway threshold and the point where the complete stop of the aircraft is achieved (see Figure 40) [28]. It is assumed that [28]: Figure 40 - Actual Landing Distance [15]. The approach speed is defined as in paragraph 6.1-b) The pilot applies maximum braking with the antiskid system operational The ground spoilers are operating No reverser thrust credit is considered 39

52 As in the takeoff situation, landing distance data must include correction factors for no more than 50% of the nominal wind components along the landing path opposite to the landing direction, and no less than 150% of the nominal wind components along the landing path in the landing direction [15]. b) Automatic Landing For an automatic landing, and on a dry runway, ALD is defined as follows [15]: Where Da is the airborne distance phase (see Figure 41) and Dg the distance covered during the ground role phase (see Figure 42). (24) Figure 41 - Airborne phase for an automatic landing [15]. The airborne phase distance (Da) corresponds to the sum of d1 and d2 plus three times the standard deviation of d2, where d1 is the distance from the runway threshold up to the glideslope origin and d2 is the distance between the origin and the mean touchdown point. The standard deviation has been statistically established from the results of more than one thousand simulated automatic landings [15]. Figure 42 - Ground role phase for an automatic landing [15]. The ground phase (Dg) for an automatic landing is established the same way as for the manual landing, assuming a touchdown speed equal to the mean touchdown speed (V TD ) plus three times the standard deviation of this speed ( ) [15] Required Landing Distance (RLD) The Required Landing Distance (RLD) is deduced from the demonstrated ALD by applying a margin coefficient that depends on the runway state, the type of landing (manual or automatic) and the regulation [29]. Before departure, operators must check that the LDA at destination is at least equal to the Required Landing Distance (RLD) for the forecasted landing weight and conditions: (25) 40

53 It is assumed that the aircraft will land on the most favorable runway, considering the probable wind speed, direction and other conditions such as landing aids and terrain (JAR-OPS (c)). Operators must take into account the runway slope, when its value is greater than ± 2%, otherwise, it is considered to be null [15]. In the event of an aircraft system failure prior to takeoff, RLD is equal to the RLD without failure multiplied by the coefficient given in the MEL, or to the performance with failure given by the Flight Manual [15]. a) Manual Landing For manual landing, regulation defines the required landing distances as the actual landing distance divided by 0.6, assuming the surface is dry: If the surface is wet, the required landing distance must be at least 115% of that for a dry surface [28]: (27) For contaminated runways, the required landing distance must be 115% of the landing distance determined in accordance with approved contaminated runway distance data (ALD for contaminated runway) and greater than the required for the wet condition: (26) { } (28) For contaminated runways, the manufacturer must provide landing performance for speed V at 50 feet above the airport, such that [15]: In certain contaminated runway cases, the manufacturer can provide detailed instructions such as those on the use of antiskid, reversers, airbrakes, or spoilers. And, in the most critical cases, landing can be prohibited [15]. (29) b) Automatic Landing As for the automatic landing case, according to regulation the required landing distance is defined as the actual landing distance (ALD) in automatic landing multiplied by This distance must be retained for automatic landing whenever it is greater than the required landing distance in manual mode [28]: { } Runway Slope A positive slope increases the aircraft stopping capability and consequently produces a decrease in the landing distance. A downward slope results in the opposite, increasing the landing distance [15]. 41

54 6.3. Go-Around Requirements Aircraft Certification a) Approach Climb The approach climb corresponds to an aircraft s climb capability, assuming that one engine is inoperative, and considering the following approach configuration (JAR ): Configuration 2 or 3 (for Airbus FBW aircraft) 14 One-Engine-Inoperative TOGA thrust Gear retracted 1.23 V s1g V 1.41 V s1g V > V MCL Notice that an approach configuration can be selected, as long as resulting stall speed does not exceed 110% of VS1g of the related all-engines-operating landing configuration. Under these circumstances the following minimum climb gradients must be demonstrated: Minimum Climb Gradient (OEI) Nº of Engines Approach Climb Twin 2.1 % Quad 2.7 % Table 13 - Minimum climb gradients during approach climb (OEI) [15]. b) Landing Climb The landing climb constraint ensures an aircraft s climb capability in case of a missed approach with all engines operating, assuming the landing configuration (JAR ). Landing configuration [15]: Configuration 3 or Full (for Airbus FBW aircraft) All engines operating Thrust available 8 seconds after initiation of thrust control movement from minimum flight idle to TOGA thrust Gear extended 1.13 V s1g V 1.23 V s1g V V MCL Under these conditions, the minimum gradient to be demonstrated is 3.2% for all aircraft types Performance Limitation When for some reason the pilot rejects a landing (while within the decision height) he must perform the Missed Approach (see dashed blue line in Appendix D) or the Go-Around procedure. In the later, the aircraft climbs into the go-around circuit (Figure 43), maneuvering into position for a new approach and landing [30]. 14 for landing in configuration 3 or Full, respectively 42

55 Figure 43- Go-around procedure [15]. A minimum climb gradient must be observed in case of a go-around. The minimum climb gradients may depend on the aircraft type and are subject to runway specifications. The goaround performance encompasses the Approach Climb Gradient (ACG) and the Landing Climb Gradient (LCG) limitations [29]. a) Approach Climb Gradient (ACG) The landing climb minimum gradient never results in a performance limitation [29], consequently, during dispatch, only the approach climb gradient needs to be checked, as this is the limiting one [15, p. 123]. TAP only operates landings of CAT II approach types, in which the minimum climb gradient is 2.5% (for all aircraft types), or greater if the approach charts require a higher value for obstacle consideration (JAR-OPS (a)). For example, for runway 21R of OR Tambo International Airport (Johannesburg) there are various go-around procedures with different minimum climb gradients (2.5, 3.7 and 5.1%) see APPENDIX D FAJS-21R Outside Elements a) Pressure Altitude Approach speed is equal to 1.23 V s1g. But, the corresponding TAS increases with the pressure altitude [15]. Consequently, the landing distance will also increase. Additionally, as seen before, TOGA thrust decreases with altitude, therefore, in the event of a go-around, a decrease in engine thrust implies a decrease in the air climb gradients. Summing up: Figure 44 - Pressure altitude influence in the landing performance [15]. b) Outside Air Temperature As seen before, in chapter 3.2.5, engine thrust decreases with temperature, when past the reference temperature. Therefore, the air climb gradients imposed in the go-around procedure will decrease. 43

56 c) Runway Condition The definition of runway conditions is the same as for takeoff (see chapter 4.4.4). When the runway is contaminated, landing performance is affected by the runway s friction coefficient, and the precipitation drag due to contaminants. A more detailed description of the physical processes involved can be seen in APPENDIX B Performance on Wet and Contaminated Runways Limitation Summary In conclusion, the landing limitations resulting from the all the former definitions and regulatory constraints, which were presented throughout this chapter, can be summarized in the following table: Code Limitation 1 Structural Weight 2 LDA 3 Approach Climb 4 Landing Climb 5 Tire Speed 6 Brake Energy Table 14 Landing limitations [26]. 44

57 7. Takeoff and Landing Performance Application (TLP) This section focuses directly on the computational application that was developed during the present work. Notice that this chapter does not intend to replace the user s manual 15 for the TLP application. Instead, the author will focus on the application structure, databases and the OCTOPUS program, which is responsible for all the performance calculations Structure The following diagram illustrates the relations between TLP and all the external agents (user, OCTOPUS program and databases): Figure 45 - TLP structure. The TLP application uses two databases, the LPCAirport and LPCAirportAdd. The OCTOPUS program has its own set of databases which include aircraft data, CDL data, and neuronal networks. TLP runs in a single windows process and mainly in a single thread as well, whose main purpose is handling the user interface. It launches, however, additional short duration threads to 15 TLP s user s manual was supplied directly to TAP Portugal and is completely independent of the present work. 45

58 display a Please Wait animated message (see Figure 46) when it is busy (either loading data or waiting for OCTOPUS to complete its calculations in the background). Figure 46 - Please Wait animated message running in an additional thread. TLP executes in two different modes: Takeoff Optimization and Landing Optimization (Figure 47). As seen in chapter 5, the main purpose of the first mode is to optimize the takeoff weight (as a function of the sustained and the free parameters) and this way calculate MTOW and the resulting operational takeoff speeds (V 1, V R and V 2 ). In a similar way, as seen in chapter 7, the objective of the Landing Optimization mode is to calculate the MLW, the landing distances (required and actual) and the approach speed. Figure 47 - TLP on startup. TLP s user interface (Figure 48) consists in several visual basic forms that contain a series of controls (such as buttons, combo boxes, text inputs and check boxes) with which the user interacts, and this way configure the free and sustained parameters. The parameters are temporarily stored into visual basic classes and are later written to the OCTOPUS input file (see Appendix C1 (a)) so that they can be used as input for the optimization process. The OCTOPUS program is launched and ran in the background as an independent program through the windows shell function. In the meantime the TLP process stalls, launching a Please Wait message in a new thread (Figure 46), while waiting for the OCTOPUS program to successfully terminate its execution. The OCTOPUS program concludes its activity by writing an output file (see Appendix C1 (b)) with the results of the optimization. This output file is then loaded and parsed by the TLP program, presented to the user and is now ready to be exported as a real RTOW chart (see Appendix C1 (c)). The user can readjust the parameters and perform new optimizations at his will. 46

59 7.2. User Interface Overview The following figure shows the main form of TLP application. It comprises four tabs that allow switching between different pages, each one addressing a specific topic of configurable parameters. The first page targets the selection of the aircraft model (by model, plate or name) and its parameters: Figure 48 Aircraft page for the Takeoff Optimization mode. Pressing the Edit button on the Failures panel shows a new auxiliary form, the aircraft failures form (Figure 49), which will allow the user to configure the missing and inoperative aircraft items (MEL and CDL items). Figure 49 - Aircraft Failures form. The second page, the Runway tab (Figure 50), addresses the selection of the airport, respective runway and all the outside elements as well (pressure, wind and runway condition). 47

60 Figure 50 Runway page for the Takeoff Optimization mode. The Options page contains regulatory configurable parameters (Figure 51), such as the minimum level-off height that by default is set to 1500 ft (according to TAP s policy) but can be reduced down to 400 ft (according to regulation). As an advanced option, the calculation mode combo box allows exchanging between First Principle and Polynomial methods. The first is more precise and time consuming, while the second is faster but more conservative. The page also displays information about the current lineup allowances (not editable). Figure 51 - Options page for the Takeoff Optimization mode. Last but not least, the Calculation page (Figure 52) is where the user specifies the temperature vector to be optimized. The page also displays a summary of the most important parameters, allowing a quick checkup before executing the calculation by pressing the Run button. 48

61 Figure 52 - Calculation page for the Takeoff Optimization mode. For the takeoff optimization, the temperature vector consists of two sections separated by the aircraft engines reference temperature (T REF ). Above this temperature the aircraft performance changes considerably with temperature (as seen in chapter 5) so it is expected to desire a smaller step between consecutive points. The number of points in the first section is directly specified by the user. By default, the program sets the initial and last points of the second section to the first integer above T REF and T Flex Max, respectively. The following scheme illustrates the structure of the temperature vector, describing how it is internally calculated: Temperature Vector T REF N Before x step1 First Section Points before reference temperature ( ) step1 T REF step1 Second Section Points between reference and maximum flex temperature T REF T REF + step2 ( ) T Flex Max step2 step2 T Flex Max Figure 53 - Temperature vector. For the landing optimization the temperature vector is much simpler, it is only defined by the first and last point plus the precision step. Finally, after OCTOPUS concludes its operation, the output is presented in the Output form: 49

62 Figure 54 - TLP s Output for the Takeoff Optimization mode. Here, the optimization results can be exported as a PDF file (see TLP Takeoff Optimization Output), an Excel file or even printed. The user can close the Output form, readjust the parameters and perform new optimizations at will Databases and Internal Classes TLP uses the LPCAirport and LPCAirportAdd databases to acquire most of its information. They contain all the required information on TAP s aircraft and respective systems, as well on all the airports, and respective runways, with which TAP currently has (or had) ongoing operations. Both of them are external Microsoft Access databases, thus data maintenance is very simple and does not require further recompilation of the program. TLP takes advantage of the OLE DB (Object Linking and Embedding, Database) API to access both of these databases. LPCAirport is a Microsoft Access database built and maintained by TAP Portugal. Besides TLP there are other programs and projects that currently use this database (namely TAP s EFB project). Unfortunately its inherent massive size forbids the attachment of any kind of diagram that could properly represent the database. The LPCAirportAdd database was built during the development of the current work with the purpose of complementing the LPCAirport databse, adding specific on aircraft s gears and operational limits. It is expected that both databases will be fused together in the future. The takeoff (or landing) parameters, selected by the user, are internally stored and organized in a set of visual basic variables and classes. The most relevant are the Aircraft and Airport classes, together with their respective subclasses which can be seen in the Appendix C2 Visual Basic Classes (a) and (b). Notice that OCTOPUS databases are addressed later in this chapter Relevant Routines Although the program contains innumerous functions making it impossible to enumerate and describe every single one, there are some functions of special relevancy that will be addressed in this sub-chapter. 50

63 ISA Temperature calculation It was necessary to compute the ISA (International Standard Atmosphere) temperature as a function of the pressure altitude. For that purpose, the tisa function (see Appendix C3 (a)) implements the following method [9]: Where h is the pressure altitude in feet. [ C] (21) Pressure Altitude Conversion Pressure altitude is the altitude corresponding to a value of atmospheric pressure (see Figure 55) [9, pp. 4-9]. In aeronautics, it is a common practice to use the pressure altitude as a measure of altitude since the atmospheric pressure can be read by a simple pressure altimeter (which can be found in most aircraft). The pressure altimeter must be calibrated to the local altitude conversion (QNH), so that it reads the altitude above MSL. Figure 55 - Pressure Altitude function of Pressure. Consequently, it was necessary to implement functions that could calculate the standard pressure at a given altitude (pa2p see Appendix C3 (b)), and vice-versa (p2pa see Appendix C3 (c)). It was assumed ISA conditions for the temperature and that air is a perfect gas. They were based on the following equations, for altitudes inside the troposphere (above MSL and below ft) [15]: ( ) [hpa] (22) ( ) [m] (23) With: P 0 = hpa T 0 = K g 0 = m.s -2 R = J.Kg -1.K -1 (standard atmosphere at MSL) (standard temperature at MSL) (standard gravity at MSL) (Perfect gas constant) 51

64 T Flex Max, T MAX and T REF Calculation T Flex Max, T MAX and T REF are always presented in RTOW charts and consequently must be calculated by TLP as well. Since they are not computed by OCTOPUS, TLP has to calculate them internally. This task is performed by a simple function SetInitialTemperature (see Appendix C3 (d)). The LPCAirport database provides the T Flex Max for each aircraft at MSL (Mean Sea Level) and assuming ISA conditions. Additionally, it also provides the necessary coefficients to estimate the T Flex Max, T MAX and T REF as functions of the pressure altitude. Note that temperature changes with pressure altitude are roughly linear, so it can be estimated the following way: Where x is the pressure altitude and a and b are the respective temperature coefficients (provided by the LPCAirport database for each aircraft). This way, it is possible to calculate the T Flex Max with those coefficients and then calculate the temperature correction by subtracting one from another. This correction can then be used to correct T MAX and T REF as well, since they were estimated using the same (linear) process. (24) 7.5. OCTOPUS This sub-section focuses on OCTOPUS, the program responsible for all the calculations in TLP. OCTOPUS stands for Operational and Certified TakeOff and landing Performance Universal Software. This is an Airbus program that is able to compute aircraft performance calculations under regulatory constraints, and this way is able to optimize takeoff and landing performance for given runways. OCTOPUS is used for computations related to A318, A319, A320, A321, A330, A340 and A380 aircraft [26]. It was delivered by Airbus in the form of Fortran 95 source code with roughly lines of code and later compiled during this work by the Compaq Visual Fortran 6 compiler Structure OCTOPUS comprises a set of executable files, databases and temporary files: Figure 56 - OCTOPUS Structure. OCTOPUS uses specific a large group of files that contain various aircraft data (such as speeds). These aircraft databases are called OCTOBASE. The Neural database consists of a 52

65 set of neural files containing pre-computed data which can be used to initiate the calculation process. Performance penalties coming from CDL items are obtained from the CDL database. The following table enumerates all of TAP s aircraft models and their respective databases: Aircraft Model Database Neural Database A AD111C02 XD111C02.PRE A AD112E01 XD112E01.PRE A AE211C03 XE211C03.PRE A AE214B02 XE214B02.PRE A AC211B05 XC211B05.PRE A AB202C02 XB202C02.PRE A AB223A03 XB223A03.PRE A AA312B04 XA312B04.PRE Table 15 - Aircraft models and respective databases Functions OCTOPUS functions can be split in three categories (Figure 57): Aircraft data file consultations and Flight manual calculations, which are certified and Optimizations (takeoff and landing) which use regulatory calculation but which are not certified [26]. Figure 57 - OCTOPUS Functions. TLP only uses functions from the third group, specifically the Takeoff Optimizations and the Landing Optimizations functions. The Takeoff Optimizations may be performed in the point, curve, network or chart modes, while the Landing Optimizations can only be executed in point and chart. In the point computation mode, OCTOPUS optimizes the takeoff weight for a specific set of conditions. For curve and network modes, however, it is possible to set a group, or two, of additional conditions to be optimized (such as a temperature vector, and/or different wind conditions). The aim of the chart computation mode is to build a complete RTOW chart, and in the same way as the curve and network modes, also allows specifying additional groups of conditions [26]. Since TLP s goal is to optimize the aircraft performance under a specific set of conditions, and for a certain temperature vector: for the takeoff optimization mode the curve computation is adequate, while for the landing optimization it was necessary to implement a chart computation. 53

66 Calculation Methods The program has two optimization methods: first principle and polynomial methods. The first is based on classical equation resolution, hence several computations are made by integration of equations. Consequently, it is the most accurate method but also the most time-consuming. Instead, the polynomial method, being a derivative mode of the previous one, is faster but more conservative. The performance constraints are smoothed by polynomials and in certain cases a quick estimation of weight and V 2 is given by a neural network (stored in specific neural files). Polynomial coefficients are also stored in specific files, together with aircraft databases [26]. Airbus strongly recommends the use of the first principle mode to compute weight optimization for accurate calculations [26]. The polynomial method cannot be used in the following conditions [26]: runway slope greater than 1 % pressure altitude greater than 8500 ft landing gear extended turn three engine ferry flight TORA, TODA or ASDA length greater than 5000 m and lower than 2000m for A330, A340 and A380 aircraft and lower than 1700m for A318, A319, A320 and A321 aircraft. extended second segment CDL items combination of failure cases 7.6. Testing and Validation With the purpose of validating the developed software, TLP was subjected to extensive testing. Its output and corresponding RTOW charts were compared to TAP s existing charts, for a multitude of input conditions (different aircraft, runways and other parameters). Additionally, they were also compared to the results obtained by the TLO module (Takeoff and Landing Optimization) of Airbus official performance program for windows PEP (Performance Engineer s Programs). A computational methodology was developed specifically for this purpose: TLP s and TLO s outputs were automatically exported to an Excel worksheet and compared (see Sample Excel File produced during TLP validation. TLP did not fail even once Validation by Certified Software Taking into account that TLO module is not certified, an additional analysis was required. This way, this study aims at demonstrating that the results obtained with TLP, for the takeoff and landing performance optimizations, comply with AFM, a certified performance software module of PEP. Since a full demonstration for all the aircraft models in TAP fleet would be too extensive to fit the requirements of the present work, this methodology will only be applied to a single aircraft model: the Airbus A a) Takeoff According to the Flight Manual of this aircraft model (see APPENDIX E FM Page - A ), its certified performance is produced by the program module Performance Engineer s 54

67 Programs / AFM_OCTO approved FM module, with the database AB202C02 or AB202C03, in the PC version of the program Octopus 23.0 or higher. The Takeoff Performance calculation in TLP uses the Airbus calculation program OCTOPUS version and database AB202C02, for this aircraft model (see Table 15, on page 53). A number of runways were selected as representative of the operation of this aircraft, under different conditions of use that address various atmospheric conditions (temperature, pressure, runway condition - dry, wet, contaminated), or MEL items. This is the same methodology that is currently being used by TAP in the demonstration of TAP s Type B EFB Software - Takeoff Performance Calculation Module. The following table summarizes the values obtained with TLP s takeoff performance optimization for the different runways and conditions (see TLP Takeoff Optimization Output, for the RTOW chart produced by TLP for the first case in the table): RWY Conf OAT RWY QNH W/C MTOW V 1 V R V 2 ( C) Condition (hpa) (kt) (ton) (kt) (kt) (kt) LIS 03 P1 1 + F 25 DRY LIS 03 P1 1 + F 21 DRY LIS 03 P F 41 WET LIS21* F 39 WET EWR 04L 2 2 Slush ¼ EWR 04L 2 2 Cp. Snow JNB 03L 1 + F 7 DRY JNB 03L 1 + F 33 DRY Entry angle 90 in all cases Bold Thrust with BUMP 16 *Spoilers 2 Pairs INOP + All reversers INOP Table 16- TLP s takeoff optimization results. RWY TORA (m) TODA (m) ASDA (m) LIS 03 P LIS EWR 04L JNB 03L Table 17 - Selected runways lengths. Using now the Complete Takeoff function of the certified FM module of PEP, the results for the same conditions are the following, as detailed in Appendix F1 (only for the first situation): RWY OAT TOR TOD ASD V 1 V R V 2 Grad (ºC) (m) (m) (m) (kt) (kt) (kt) 2º Seg Obst LIS 03 P OK LIS 03 P OK LIS 03 P OK LIS21* OK EWR 04L OK EWR 04L OK JNB 03L OK JNB 03L OK Table 18 AFM s takeoff results. 16 BUMP is an engine setting that allows additional thrust power at the cost of reducing engine life. 55

68 Notice that the FM module takes TOW, V 1 /V R and V 2 /V S as input, consequently these values were obtained externally by PEP s TLO module: RWY OAT (ºC) V 1 /V R V 2 /V S TOW (ton) LIS 03 P LIS 03 P LIS 03 P LIS21* EWR 04L EWR 04L JNB 03L JNB 03L Table 19 - Optimum weights and ratios obtained by PEP s TLO module. Comparing the Table 17 with Table 18 it is found that the required runway lengths are lower than those available. Also, all the MTOW and V 1 values calculated by TLP (in Table 16) are lower than the ones obtained by the certified software (see Table 18). Notice that TLP rounds down to the unit the values for both MTOW and V 1 (rounds up V R and V 2 ) internally so that a more conservative result is deliberately produced. In a similar way all the values for V R and V 2 computed by TLP are higher, and more conservative, than the ones calculated by PEP s certified module. Finally, all the obstacle limitations were tested and verified as seen in Appendix F. The graphs obtained show the obstacles and the 35 feet margin providing, this way, providing a visual verification. To check this limitation, not included in the PEP s FM module function Complete Takeoff, use was made of the Takeoff Flight Path calculation option. This demonstrates the consistency of the results obtained from all of the modules. b) Landing In a similar way, the results obtained in TLP for landing optimizations were also tested against the results obtained by certified AFM software. It was considered a hypothetic situation of an Airbus A landing in Johannesburg s OR Tambo International Airport on runway 03L. This particular runway has different go-around procedures but it was assumed to consider one that required a minimum of 3.5 % for the approach climb gradient (ACG). The aircraft was assumed to use configuration Full during landing, configuration 3 for the approach and a low braking setting during ground roll. The following table describes the atmospheric conditions for the considered landing and summarizes the results obtained through TLP s landing optimization: OAT RWY QNH W/C MLW V RWY FA ALD RLD ( C) Condition (hpa) (kt) (ton) (kt) (m) (m) JNB 03L 3 Slush ¼ Table 20 - TLP landing optimization results. Like in most landing situations, the minimum approach climb gradient is the weight limiting restriction, as seen in the complete output file produced by TLP, that can be seen in Appendix C1 (d). Unlike for the takeoff situation, PEP s FM module does not have a full landing calculation function, instead, it was necessary to use a set of different functions: Approach Climb Gradient, Landing Climb Gradient, Landing Distance and Operational Landing Distance. 56

69 The Landing Distance function takes MLW as input and outputs the required landing distance imposed by regulation, which as seen in table 21 is equal to the value computed by TLP: MLW (ton) RLD (m) Computed LD (m) V FA (kt) Table 21 Required Landing Distance calculated by FM s Landing Distance function. Notice that both required landing distances are below 4418 m which is the landing distance available (LDA) for the runway 03L (see Appendix C1 (d)). The complete output file produced by the Landing Distance function can be seen in Appendix G1. According to Table 22 the actual landing distance computed by FM s Operational Landing Distance function is also below the one obtained by TLP. Additionally, since the approach speed obtained by TLP is lower than the one obtained by both FM s landing distance functions, it is also more conservative than the one calculated by PEP s FM module. For the complete Operational Landing Distance output file, see Appendix G2. MLW (ton) ALD (m) V FA (kt) Table 22 - Actual Landing Distance calculated by FM s Operational Landing Distance function. The Landing Climb Gradient function accepts the minimum landing climb gradient as input, set by regulations to 3.2 %, and outputs the maximum weight limited by LCG, among other performance data (the complete output file can be seen in Appendix G3): LCG Maximum Weight (kg) IAS (kt) 3.2 % Table 23 - Maximum weight calculated by FM s Landing Climb Gradient function. The Approach Climb Gradient function takes the minimum approach climb gradient as input (which in this case is equal to 3.5 %) and outputs several performance data, namely the maximum landing weight (the whole output file can be seen in Appendix G4): ACG Maximum Weight (kg) IAS (kt) 3.5 % Table 24 Maximum weight calculated by FM s Approach Climb Gradient function. Comparing the values from Table 23 and Table 24, we conclude that the weight limitation imposed by the LCG condition is less restrictive than the one imposed by the ACG limitation, consequently the MLW obtained by the certified software is 28 kg above the one computed by TLP. Concluding, TLP s values are sound and are more conservative than the results obtained by the certified software. 57

70 8. Conclusion Motivated by the opportunity to provide real contribution to the aviation industry, and particularly to TAP, it was with great enthusiasm that the author first started working on this project. It is with a similar feeling in pair with the added sense of accomplishment that he writes these last lines of the present dissertation. Although the current work consisted in the development of a computational application, a large initial effort was invested in the interpretation of the OCTOPUS program, namely its internal procedures, functions, databases and specially its input and output files. Undoubtedly, this was one of the most important and time-consuming stages of the dissertation; OCTOPUS is after all the backbone of the TLP program. Simultaneously, the author attended one of TAP s internal Aircraft Performance courses which proved to be of great value. It has provided not only valuable theoretical knowledge but also in loco know-how on TAP s own policy on takeoff and landing procedures. Only later, when the program s lifecycle, and consequent flowchart, became a comfort area to the author, it took place the computational development. The user interface is the outcome of an interactive process based on the experience and sensibility acquired from Airbus official performance programs (PEP) of both TAP engineers and future users of this application. The Takeoff and Landing Performance Program (TLP) is TAP s new technological solution for on-ground performance calculation. Besides providing valuable benefits for the dispatch procedures, with its dynamic and prompt reaction user interface, it will prove to be a helpful working tool for TAP s performance engineers with its vast configurable inputs and editable Excel worksheet outputs. One process that could take a couple of hours, before, can now be accomplished within seconds, providing safe and always optimal values. All in all, the author believes that the present project will prove its benefit to TAP Portugal, either by simplifying the daily activity of its engineers or by serving as a new training tool for pilots. This way, TLP places TAP one step further in the never-ending optimization process. Computer performance data calculation in cockpits is the next step in airline industry [1]. Major commercial companies have investigated the advantages of electronic computing devices in the cockpit. In 2001 UAL (United Airlines) tested an EFB device incorporating a Fujitsu Pentablet computer on an Airbus 319 aircraft with specially trained crewmembers. Since receiving a grant from the FAA in September of 2001, UAL has been developing an EFB that may become a standard for the industry [31]. Projects such as this and TAP s Electronic Flight Bag are currently pioneers in the struggle to develop certified EFBs. Primarily, EFBs are used by commercial transport pilots for the performance of flight management tasks, both during flight and in the aircraft turnaround. Currently, the range of functionality supported includes aircraft performance calculations, weather and situation displays, flight log reporting, aircraft defect reporting, communications and document viewing (checklists, aeronautical charts and maintenance manuals) [32]. There are two distinct steps proposed by Airbus for implementing this idea into life [1]. The first involves the implementation of out of the box technology low cost solutions, such as TAP s EFB. These take advantage of commercially available laptops, which can be plugged-in to the aircraft s cockpit. The next step would be server linking aircraft avionics and EFB systems, allowing aircraft manual update, enhanced flight functions, and maintenance data transfer through wireless gate-links at speeds 100 times faster than today s Aircraft Communication and Reporting System (ACARS) [33]. 58

71 9. References [1] I. Sikora, S. Pavlin and E. Bazijanac, "The Example of Laptop Based Performance Data Generating and Optimization in Contemporary Commercial Aircraft Operations," in ISEP'99, [2] TAP, Guia de Integração de Estagiários, TAP, [3] TAP, "TAP, S.A. obtém o Melhor Resultado de Sempre," Commercial Airliner, 10 March [Online]. Available: [4] A. Cento, The Airline Industry: Challenges in the 21st Century, Physica-Verlag, [5] Air Transport Association, "2010 Economic Report," Air Transport Association, [6] B. Alukos, "Fuel Prices - The Airline Industry's Toughest Headwind," Industry Reports, 09 April [Online]. Available: [7] Centre for Asia Pacific Aviation, "US airlines look to international markets for future growth," Aviation Market Intelligence, 18 August [Online]. Available: [8] S. K. Ojha, Flight Performance of Aircraft, Wright-Patterson Air Force Base, Ohio: American Institute of Aeronautics and Astronautics, [9] W. Blake, Jet Transport Performance Methods, Boeing, [10] FAA, Instrument Procedures Handbook, Skyhorse Publishing, [11] Airbus, A340 Flight Deck and Systems Briefing for Pilots, Airbus, [12] C. Anhalt, E. Breitbach and D. Sachau, "A Concept of a Shapevariable Fowler Flap on Transport Aircraft," German Aearospace Center (DLR), Braunschweig, Germany, [13] Airbus, A330 Flight Deck and Systems Briefing for Pilots, Airbus, [14] Airbus, A320 Flight Deck and Systems Briefing for Pilots, Airbus, [15] Airbus, Getting to Grips With Aircraft Performance, Airbus Customer Services, [16] FAA, "Volume 4: Aircraft Equipment and Operational Authorizations," in FSIMS, FAA, [17] Airbus, "Flight Operations Briefing Notes," Airbus, [18] A. Aguiar and C. Figueiredo, Aeroplane Performance, TAP, [19] TAP, A320 Flight Crew Operating Manual - Part 2: Flight Preparation, TAP,

72 [20] TAP, A320 Flight Crew Operating Manual - Part 3: Flight Operations, TAP, [21] Airbus, "Limitations - Power Plant," in A330-A340 FCOM, Airbus. [22] TAP, A330-A340 Flight Crew Operating Manual - General Information, TAP, [23] V. d. Brederode, Fundamentos de Aaerodinâmica Incompressível, Instituto Superior Técnico, [24] M. Fueri, "Flex Temperature, Choice of Configuration," in 14th Performance & Operations Conference, Bangkok, [25] A. Aguiar, Aeroplane Performance, TAP, [26] Airbus, Performance Programs Manual, Airbus, [27] TAP, "A Airport Analysis," TAP, [28] TAP, A330-A340 Flight Crew Operating Manual - Performance, TAP, [29] E. Lesage, "LPC Landing," in 12th Performance and Operations Conference, Rome, [30] D. Crocker, Dictionary of Aviation, London: A&C Black Publishers, [31] M. F. S. Fitzsimmons, "The Electronic Flight Bag," United States Air Force Academy, Colorado, [32] J. Cahill and N. M. Donald, "Human Computer Interaction Methods for Electronic Flight Bag," Cogn Tech Work, [33] D. Michael, "Less Paper in the Cockpit," in 10th Performance and Operations Conference, San Francisco, [34] FAA, "Joint Aircraft System / Component Code," FAA, Oklahoma,

73 APPENDIX A Regulation Transcripts A1. JAR 25 Subpart B Transcripts This section contains transcripts from Joint Aviation Requirements, issued by the Joint Aviation Authorities. The full document can be purchased from Global Engineering Documents, whose worldwide offices are listed on the JAA website ( and Global website ( JAR (Weight Limits) (a) Maximum weights. Maximum weights corresponding to the aeroplane operating conditions (such as ramp, ground taxi, take-off, en-route and landing) environmental conditions (such as altitude and temperature), and loading conditions (such as zero fuel weight, centre of gravity position and weight distribution) must be established so that they are not more than - The highest weight selected by the applicant for the particular conditions; or The highest weight at which compliance with each applicable structural loading and flight requirement is shown. (b) Minimum weight. The minimum weight (the lowest weight at which compliance with each applicable requirement of this JAR-25 is shown) must be established so that it is not less than - The lowest weight selected by the applicant; The design minimum weight (the lowest weight at which compliance with each structural loading condition of this JAR-25 is shown); or The lowest weight at which compliance with each applicable flight requirement is shown. JAR (Stall Speed) (a) The reference stall speed, VSR, is a calibrated airspeed defined by the applicant. VSR may not be less than a 1-g stall speed. VSR is expressed as: where: VCLMAX nzw W S = Calibrated airspeed obtained when the load factor-corrected lift coefficient ( ) is the first maximum during the maneuver prescribed in paragraph (c) of this section. In addition, when the maneuver is limited by a device that abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher), VCLMAX may not be less than the speed existing at the instant the device operates; = Load factor normal to the flight path at VCLMAX; = Aeroplane gross weight; = Aerodynamic reference wing area; and 61

74 Q = Dynamic pressure. (c) Starting from the stabilized trim condition, apply the longitudinal control to decelerate the airplane so that the speed reduction does not exceed one knot per second. JAR (Takeoff Speeds) (a) V1 must be established in relation to VEF as follows: VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under JAR (e). V1 in terms of calibrated airspeed, is the take-off decision speed selected by the applicant; however, V1 may not be less than VEF plus the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognises and reacts to the engine failure, as indicated by the pilot's application of the first retarding means during accelerate-stop tests. (b) V2min, in terms of calibrated airspeed, may not be less than: VSR for turbo-jet powered aeroplanes [ ] 1.10 times VMCA (c) V2, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by JAR (b) but may not be less than: V2min; and VR plus the speed increment attained before reaching a height of 35 ft above the takeoff surface. (d) VMU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and continue the takeoff. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground takeoff tests. (e) VR, in terms of calibrated air speed, must be selected in accordance with the conditions of paragraphs (e) (1) through (4) of this section: VR may not be less than: - V1, - 105% of VMCA - The speed that allows reaching V2 before reaching a height of 35 ft above the take-off surface, or - A speed that, if the aeroplane is rotated at its maximum practicable rate, will result in a VLOF of not less than 1 10% of VMU in the all-engines-operating condition and not less than 105% of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition, except that in the particular case that lift-off is limited by the geometry of the aeroplane, or by elevator power, the above margins may be reduced to 108% in the allengines-operating case and 104% in the one-engine-inoperative condition. (See ACJ 25. I07(e)( i)(iv). ( ) 62

75 (f) VLOF is the calibrated airspeed at which the aeroplane first becomes airborne. JAR (Take-off distance and take-off run) (a) Take-off distance on a dry runway is the greater of: The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, determined under JAR for a dry runway;or 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, as determined by a procedure consistent with JAR (See ACJ (a)(2).) (b) Take-off distance on a wet runway is the greater of: The take-off distance on a dry runway determined in accordance with sub-paragraph (a) of this paragraph; or The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2, before reaching 35 ft above the take-off surface, determined under JAR for a wet runway. (See ACJ 113(a)(2).) (c) If the take-off distance does not include a clearway, the take-off run is equal to the take-off distance. If the take-off distance includes a clearway: The take-off run on a dry runway is the greater of: - The horizontal distance along the take-off path from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, as determined under JAR for a dry runway; or - 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, determined by a procedure consistent with JAR (See ACJ (a)(2).) The take-off run on a wet runway is the greater of: - The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 ft above the take-off surface, determined under JAR for a wet runway; or - 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, determined by a procedure consistent with JAR (See ACJ (a)(2).) JAR (Minimum control speed) (b) VMC[A] is the calibrated airspeed, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5 degrees. 63

76 (c)vmc[a] may not exceed 1.2 VS with: Maximum available take-off power or thrust on the engines; The most unfavourable centre of gravity; The aeroplane trimmed for take-off; The maximum sea-level take-off weight JAR (Minimum Control Speed) (e) VMCG, the minimum control speed on the ground, is the calibrated airspeed during the take-off run, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with the use of the primary aerodynamic controls alone (without the use of nose-wheel steering) to enable the take-off to be safely continued using normal piloting skill. In the determination of VMCG, assuming that the path of the aeroplane accelerating with all engines operating is along the centreline of the runway, its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centreline is completed, may not deviate more than 30 ft laterally from the centreline at any point. JAR (Minimum Control Speed) (f) VMCL, the minimum control speed during approach and landing with all engines operating, is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5º. VMCL must be established with: The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with all engines operating; The most unfavourable centre of gravity; The aeroplane trimmed for approach with all engines operating; The most unfavourable weight, or, at the option of the applicant, as a function of weight. Go-around thrust setting on the operating engines (g) For aeroplanes with three or more engines, VMCL-2, the minimum control speed during approach and landing with one critical engine inoperative, is the calibrated airspeed at which, when a second critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with both engines still inoperative, and maintain straight flight with an angle of bank of not more than 5 degrees. VMCL-2 must be established with [the same conditions as VMCL, except that]: The aeroplane trimmed for approach with one critical engine inoperative The thrust on the operating engine(s) necessary to maintain an approach path angle of 3 degrees when one critical engine is inoperative The thrust on the operating engine(s) rapidly changed, immediately after the second critical engine is made inoperative, from the [previous] thrust to: - the minimum thrust [and then to] - the go-around thrust setting (h) In demonstrations of VMCL and VMCL-2, lateral control must be sufficient to roll the aeroplane from an initial condition of steady straight flight, through an angle of 20 degrees in the direction necessary to initiate a turn away from the inoperative engine(s) in not more than 5 seconds. 64

77 A2. AMJ Transcripts AMJ "(4)(c) Reduced takeoff thrust, for an aeroplane, is a takeoff thrust less than the takeoff (or derated takeoff) thrust. The aeroplane takeoff performance and thrust setting are established by approved simple methods, such as adjustments, or by corrections to the takeoff thrust setting and performance. (5)(a) The reduced takeoff thrust setting Is based on an approved takeoff thrust rating for which complete aeroplane performance data is provided Enables compliance with the aeroplane controllability requirements in the event that takeoff thrust is applied at any point in the takeoff path Is at least 75% of the maximum takeoff thrust for the existing ambient conditions (f) The AFM states that [reduced thrust takeoffs] are not authorised on contaminated runways and are not authorised on wet runways unless suitable performance accountability is made for the increased stopping distance on the wet surface. 65

78 APPENDIX B Performance on Wet and Contaminated Runways This appendix on performance on wet and contaminated runways has the purpose of providing a better understanding on the physical processes that take place on non-dry runways. Different runway conditions will have different effects on the acceleration and deceleration characteristics of an airplane. Wet and slippery runways will affect the aircraft s deceleration capability without affecting its acceleration. Standing water, slush and loose compactible snow will affect an airplane s acceleration capability as well as its deceleration. For that reason, runway contaminants are divided into two different categories: solid contaminants and loose contaminants [9]. Solid contaminants affect deceleration but have no effect on acceleration. This category includes ice and compact snow. Loose contaminants add a component of drag, retarding the aircraft s motion and thus affect both acceleration and deceleration. This includes loose snow and slush or standing water with more than inches deep. 7.2 Solid Contaminants Solid contaminants have a direct impact on aircraft braking coefficient. In general a wet runway has less friction available for stopping an aircraft in an emergency. How much the runway friction is reduced by moisture on the surface of the runway is a function of the material and techniques of runway construction [9]. JAR , paragraph (c) provides equations for the wet runway maximum braking coefficient (tire-to-ground) as a function of tire pressure and airplane ground speed: Tire Pressure (psi) ( ) Maximum Braking Coefficient (tire-to-ground) 50 ( ) ( ) ( ) 100 ( ) ( ) ( ) 200 ( ) ( ) ( ) 300 ( ) ( ) ( ) Where V is the true ground speed in knots; note that linear interpolation is allowed for tire pressures other than the listed above. As an example, for a tire pressure of 200 psi the maximum friction coefficient defined by the equation will be as shown in Figure

79 Figure 58 - Aircraft braking coefficient for a 200 psi tire pressure on a wet runway [9]. For its determination of the aircraft maximum braking coefficient on wet runways aircraft manufacturers use a tire pressure which is approximately at the top of the range of tire pressures for a given aircraft [9]. The maximum tire-to-ground wet runway braking coefficient of friction ( ) must be adjusted to take into account the efficiency of the anti-skid system on a wet runway. Anti-skid system operation must be demonstrated by flight testing on a smooth wet runway, and its efficiency must be determined [9]. Based on the equations and the results of flight testing, then, aircraft manufacturers are able to find a definition of the wet runway airplane braking coefficient for each aircraft, as shown in Figure 59. Figure 59 - Aircraft braking coefficient on a wet runway [9]. Because aircraft braking coefficient is a function of ground speed, the calculation of the stopping distance on wet runways does not use a single constant value of as for dry runways. Instead, the step integration of stopping distance will use a changing value of decreases [9]. as the speed For solid contaminants other than wet or wet skid-resistant there is no universally accepted relationship between runway description, reported braking action, and airplane performance. The airplane s actual performance may well be different for the same description of the runway 67

80 surface or the pilot-reported braking action. Aircraft manufacturers have been choosing, based on experience, a relationship of reported braking action to airplane braking coefficient. This relationship has been used to create the published data [9]. 7.3 Loose Contaminants The physics of takeoff on a runway having loose contaminants (see Figure 60) are similar to those on a dry runway, with one notable exception: the addition of the drag on the airplane resulting from the material which is covering the runway, be it standing water, slush, or wet snow [9]. Figure 60 - Physics of contaminant drag [9]. Contaminant drag actually has two elements: displacement drag and impingement drag. As illustrated in Figure 61, displacement drag results from the energy required for the landing gear tires to displace the contaminant that is, to move it out of their way as the airplane rolls along the runway [9]. Impingement drag results from the airplane kinetic energy lost due to the impact of contaminant on parts of the body (see Figure 62). The passage of the wheels through the contaminant causes a very powerful spray to be thrown up; due to its density and the velocity at which it strikes the airplane, it creates considerable impact force on the airplane. Since this impact force is in an aftward direction, it subtracts from the airplane s kinetic energy [9]. Figure 61 Displacement Drag [9]. Figure 62 - Impingment Drag [9]. The contaminant impact can actually cause physical damage to an aircraft. As a result of this, and because of the increasingly adverse effect of loose contaminants on takeoff performance as depth increases, the FAA and JAA both state specifically that takeoff is prohibited on runways having more than ½ inch (FAA) or 12.7 millimeters (JAA) of loose contaminant. The latest EASA regulations on non-dry runways, however, permit up to 15 millimeters instead of the earlier 12.7 mm (or ½ inch) [9]. 68

81 Additionally, hydroplaning, or aquaplaning, is a dynamic condition encountered by an aircraft s tires when operating on runways covered with loose contaminant. At low speeds on a runway having loose contaminant there is adequate time for the contaminant to move away from an aircraft s tires as it accelerates down the runway for takeoff, allowing the tires to remain in solid contact with the runway surface. The presence of the contaminant does result in an increase of the airplane s drag, as discussed above, but there are no other adverse effects. However, as an aircraft accelerates in loose contaminant, the tires cause an increase of pressure in the contaminant in the area immediately ahead of them. When that pressure becomes sufficiently great, it forces a wedge of fluid underneath the tires leading edges, thus lifting the tires out of contact with the runway surface resulting in a loss of traction [9]: Figure 63 Hydroplaning effect [9]. The speed at which hydroplaning commences during an acceleration is known as the hydroplaning speed V HP. It s a function of tire pressure. The EASA s accepted equation for the hydroplaning speed is: The following figure illustrates the repercussions that the different contaminants have on the takeoff distance, for the same weight ( tons) and V 1 (160.6 kt), on a dry runway with meters long (11,000 ft): Figure 64 - Effect of contaminants on takeoff distances [9]. 69

82 APPENDIX C TLP C1. Files a) OCTOPUS Input FILE FORMAT NUMBER : 185 CALCULATION FILE NAME : INPUT OCTOPUS VERSION : *AIRCRAFT FILE :.\octopus\precal\ac211b05 *FLIGHT MANUAL VERSION : 9 PRECALCULATION FILE : OBSOLETE NEURONAL FILE : OBSOLETE *AFM NEURONAL FILE :.\octopus\precal\xc211b05.pre *REGULATION : 1 *CALCULATION NAME : 15 *CALCULATION MODE (1=POINT 2=CURVE 3=NET : 2 *CDL DATA FILE NAME :.\octopus\precal\cdldata *CDL DATA FILE ISSUE : UNITS *LENGTH UNIT (1=M 2=FT 3= NAUTICAL MIL : 1 *ALTITUDES UNIT (1=M 2=FT) : 2 *FORCES UNIT (1=DAN 2=LB) : 1 *HORIZONTAL SPEED UNIT (1=M/S 2=KM/H 3=K : 3 *VERTICAL SPEED UNIT (1=M/S 2=FT/MN) : 1 *PRESSURES UNIT (1=HPA 2=IHG) : 1 *TEMPERATURE UNIT (1=DEG C 2=DEG F) : 1 *WEIGHT UNIT (1=KG 2=LB) : 1 *TIME UNIT (1=SEC 2=MN 3=H) : AIRCRAFT DATA WEIGHT : WEIGHT INITIAL POINT : MAXIMUN STRUCTURAL WEIGHT : MAXIMUN STRUCTURAL WEIGHT FOR LANDING : *CONFIGURATION (CF SUM GLO : 3 CONFIGURATION INITIAL POINT (CF SUM GLO : 1 CG FORWARD POSITION : *CG FORWARD LIMIT CODE (1=BASIC 2=ALTERN : 1 FLIGHT CG : FLIGHT CG INITIAL POINT : LANDING GEAR POSITION INITIAL POINT : 1 MAXIMUM PITCH ATTITUDE : *DEICING VALVE FAILURE (1=NO 2=YES) : 1 CD DETERIORATION : *CDL DEGRADATION : ( ) *NUMBER OF NEGLIGIBLE CDL ITEMS : 0 CL DETERIORATION : CL MAX DETERIORATION : EFFECT ON STALL SPEED (LIP) (1=NO 2=YES : 1 JETTISON FUNCTION : 1 WEIGHT FOR END OF JETTISON : STEEP APPROACH LANDING (1=NO 2=YES) : 1 STEEP APPROACH GLIDE : OVERWEIGHT LANDING (1=NO 2=YES) : 1 IN FLIGHT FAILURE CASES : ( ) CG VALUE FOR IN FLIGHT FAILURE CASES : REFUELING PODS : 1 REFUELING BOOM : 1 70

83 ATMOSPHERE DATA RELATIVE HUMIDITY TYPE : 1 RELATIVE HUMIDITY : PRESSURE : CURRENT PRESSURE ALTITUDE (NOT USED) : TEMPERATURE TYPE (1=OAT 2=DISA) : 1 TEMPERATURE : *WIND IN X AXIS : *WIND IN Y AXIS : WIND : ENGINE DATA *AIR COND (1=OFF 2=ON 3=ECO 4=MAX) : 1 *ANTI-ICING (1=OFF 2=ENG 3=ENG+AIRF) : 1 AIR COND INITIAL POINT (CF AIR COND) : 1 ANTI-ICING INITIAL POINT (CF ANTI-ICING : 1 ENGINE CALIBRATION LEVEL (1=MAX 2=AVER : 1 DERATING (CF AIRCRAFT FILE) : 1 *ENGINE OPTION : 1 DELTA fn DETERIORATION : FLEXIBLE TEMPERATURE : FLEX TAKE OFF (1=NO 2=YES) : 1 *GROUND IDLE FAILURE (1=NO 2=YES) : 1 NUMBER OF INOPERATIVE ENGINES : 1 K FN DETERIORATION : ONE ENGINE OUT FERRY FLIGHT (1=NO) : 1 FIXED PMP VALUE INITIAL POINT : FIXED PMP VALUE : *REVERSE CREDIT (1=ALL REV INOP., 2=ALL : 1 FIXED THRUST VALUE : THRUST LEVEL : 1 DISPATCH IN N1 MODE : GEARS DATA *ANTISKID (1=ON 2=OFF 3=PART. OFF) : 1 *AUTOBRAKES (1=OFF) : 1 *BRAKING FAILED (1=0 BRAKE INOPERATIVE 2 : 1 BRAKING FAILED CENTRAL GEAR (1=0 BRAKE : 1 BRAKING FAILED WING GEAR (1=0 BRAKE INO : 1 BRAKING FAILED BODY GEAR (1=0 BRAKE INO : 1 BRAKE MODE (CF SUM GLOSSARY) : 1 CENTRAL GEARS RETRACTED (1=NO 2=YES) : 1 *LANDING GEAR EXTENDED (1=NO 2=YES) : 1 LANDING GEARS POSITION (1=UP 2=DOWN) : 1 *HYDRAULIC PUMP FAILURE (1=NO 2=YES) : 1 *TACHOMETER FAILURE (1=NO 2=YES) : REGULATION DATA *LOWEST LIM. GROSS LEV.-OFF HEIGHT TYPE : 2 *LOWEST LIM. GROSS LEV.-OFF HEIGHT : *OBSTACLE CLEARANCE (1=NORM 2=15 FT 3=35 : 1 *SCREEN HEIGHT AT END OF RUNWAY : RUNWAY DATA NUMBER OF RUNWAYS : 1 *ALIGMENT ALLOWANCE SELECTION (1=STANDAR : 1 ALIGMENT 0 DEGREE (TODA,TORA) : ALIGMENT 0 DEGREE (ASDA) : ALIGMENT 90 DEGREE (TODA,TORA) : ALIGMENT 90 DEGREE (ASDA) : ALIGMENT 180 DEGREE (TODA,TORA) : ALIGMENT 180 DEGREE (ASDA) : ALIGMENT 180PAD (TODA,TORA) : ALIGMENT 180PAD (ASDA) : ALIGMENT 180 OTHER (TODA,TORA) : ALIGMENT 180 OTHER (ASDA) : CURRENT RUNWAY NUMBER : 1 71

84 *AIRPORT IDENTIFICATION : LISBOA *RUNWAY IDENTIFICATION : 17 *ICAO CODE : LPPT *IATA CODE : LIS RUNWAY QFU : 17 *RUNWAY SLOPE : HEADING : *RUNWAY ALTITUDE TYPE (1=ZP 2=QNH 3=QFE) : 2 *RUNWAY PRESSURE ALTITUDE : *RUNWAY GEOMETRIC ALTITUDE : *RUNWAY LENGTH REPRESENTATION (1=TODA-AS : 1 *ASDA OR STOPWAY : *MULTIPLICATION FACTOR ON ASDA : *INCREMENT VALUE ON ASDA : *ALIGNMENT ALLOWANCE FOR ASDA : *TODA OR CLEARWAY : *AVAILABLE RUNWAY DIST.(TORA) : *ALIGNMENT ALLOWANCE FOR TORA AND TODA : ENTRY ANGLE : 2 ENTRY ANGLE (UNUSED) : 1 LDA : ADDITIVE COEFFICIENT ON LDA : MULTIPLICATIVE OEFFICIENT ON LDA : *RUNWAY STATE (1=DRY 2=WET 3=WATER_1/4" : 1 RUNWAY SURFACE (1=SMOOTH 2=GROOVED/PFC) : 1 STOPWAY SURFACE (1=SMOOTH 2=GROOVED/PFC : 1 RUNWAY TEMPERATURE : REFERENCE FOR OBSTACLE DEFINITION : 2 *NUMBER OF OBSTACLES : 1 *OBSTACLE X POSITIONS : ( ) ( ) ( ) *OBSTACLE Y POSITIONS : ( ) ( ) ( ) *OBSTACLE H POSITIONS : ( ) ( ) ( ) OBSTACLE SELECTION (1=ALL 2=SPLAY) : 2 FLIGHT PATH SPLAY ANGLE : INITIAL FLIGHT PATH HALFWIDTH : FINAL FLIGHT PATH HALFWIDTH : *RUNWAY WIDTH : RUNWAY + STAB. SHOULDER WIDTH LT 58M : 1 *COMMENT LINE 1 FOR TAKE-OFF : *COMMENT LINE 2 FOR TAKE-OFF : COMMENT LINE 1 FOR LANDING : COMMENT LINE 2 FOR LANDING : APPROACH GRADIENT (RUNWAY) : DELTA ALTITUDE FOR ACG CALCULATION : ILS GLIDE (RUNWAY) : SPOILERS DATA *SPOILERS (1=ALL SP OPER 2=ALL SP INOP 3 : 1 AILERON ANTI DROOP FUNCTION (1=NO 2=YE : TURNS DATA *TURN OPTION (1=YES 2=NO) : 2 NUMBER OF TURN : 0 *TURN TYPE 2 *TURN VALUE *START TURN POINT TYPE 2 *START TURN POINT VALUE *END TURN POINT TYPE 5 *END TURN POINT VALUE 72

85 SPEED DATA SPEED VALUE (or V/VS) : V1 TYPE (1=V1/VR 2=CAS 3=IAS) : 1 V1 (or V1/VR) VALUE : V2 TYPE (1=V2/VS 2=CAS 3=IAS) : 1 V2 (OR V2/VS) VALUE : VC VALUE : SPEED TYPE (1=V/VS 2=CAS 3=IAS) : 1 V/VS VALUE : V1 LIMITATION CODE (1=MIN 2=MAX 3=BALAN : PERFORMANCE DATA MODELISATION (1=AFM 2=POLYNOMIALE 3=NEU : 0 CATEGORY II APPROACH (1=NO 2=YES) : 1 DELTA V (CAS) : ND SEGMENT GRADIENT VALUE : GRADIENT VALUE : SPEED (OR K) VALUE : LANDING CONFIGURATION : 1 GRADIENT CALCULATION WITH REGULATORY VA : 2 WEIGHT OR GRADIENT CALCULATION : 1 *EXTENDED SECOND SEGMENT : 2 REGULATORY COEFFICIENT : SSG OR WEIGHT CALCULATION : 1 ETOPS LAW : 1 CAS FOR USER'S ETOPS LAW : MACH FOR USER'S ETOPS LAW : LANDING IN CLEAN CONFIGURATION : 1 USER' DECELERATION : NET CEILING CALCULATION (1=NO 2=YES) : 1 DRIFT-DOWN CALCULATION (1=NO 2=YES) : 1 AUTOLAND CALCULATION (1=NO 2=YES) : 1 GLIDE FOR AUTOLAND : RUNWAY SLOPE FOR AUTOLAND : TEMPERATURE OPTION FOR AUTOLAND : 1 TEMPERATURE FOR AUTOLAND : PRESSURE ALTITUDE FOR AUTOLAND : VMBE CALCULATION (1=NO 2=YES) : 1 CALCULATION OPTION (1=DISTANCE 2=WEIGHT : 1 DISTANCE VALUE FOR WEIGHT CALCULATION : FTO CHECK (1=YES 2=NO) : ADDITIVE VMC DATA VMC TYPE : 1 DISA TEMPERATURE : ADDITIVE AIRSPEED CALIBRATION DATA GROUND CONTACT : 1 CONTEXT (1=TAKEOFF 2=LANDING) : TAKE OFF OPTIMIZATION DATA *OPTIMIZATION TYPE (1=POLYNOMIAL 2=FIRST : 2 OPTIMIZATION METHOD (1=DEGREE 2 2=SIMPL : 0 MODELISATION (1=POLYNOMIALE 2=NEURAL) : 0 *OUTPUT LEVEL (1=VERY SHORT 2=SHORT 3=FU : 2 *V1/VR CALCULATION MODE (1=FULL RANGE 2= : 1 *V2/VS CALCULATION MODE (1=FULL RANGE 2= : 1 V1/VR MIN : V1/VR MAX : V2/VS MIN : V2/VS MAX : DRY/WET COMPARAISON : 2 *ACG CHECK : 1 *AQUAPLANING EFFECT ON DRAG (1=NORMAL 2= : 1 *CHECK VS 1/4" (6.3MM) CONT DEPTH (1=NO : 1 73

86 *TFLEX MAX DISA : CONSTRAINT DEGRADATIONS DATA *COEF. TOD1 : *ADD. TOD1 : *COEF. TOR1 : *ADD. TOR1 : *COEF. TOD0 : *ADD. TOD0 : *COEF. TOR0 : *ADD. TOR0 : *COEF. ASD1 : *ADD. ASD1 : *COEF. ASD0 : *ADD. ASD0 : *COEF. FSG : *ADD. FSG : *COEF. SSG : *ADD. SSG : *COEF. FTO : *ADD. FTO : *COEF. VMCG : *ADD. VMCG : *COEF. VMCA : *ADD. VMCA : *COEF. VMU : *ADD. VMU : *COEF. ENERGY RATIO : *ADD. ENERGY RATIO : COEF. ACG : ADD. ACG : COEF. LCG : ADD. LCG : COEF. LD : ADD. LD : COEF. VMCL : ADD. VMCL : *COEF. VTYRE : *ADD. VTYRE : CALCULATION MODE *ABSCISSA : 6 *ABSCISSA VALUES : ( ) ( ) ( ) ISO : 4 ISO VALUES : ( ) ( ) b) OCTOPUS Output CALCULATION FILE NAME : INPUT OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AC211B05 A /V I INPUT DATA RECAPITULATION I 74

87 Take-off optimization type : FIRST PRINCIPLE METHOD Level of output : SHORT V1/VR calculation mode : FULL RANGE V2/VS calculation mode : FULL RANGE Extended second segment : NO Screen height at end of runway : NORMAL Obstacle clearance : NORMAL Low. lim. gross level-off height option : VALUE Lowest limitation gross level-off height: FT Aquaplaning effect on drag : NORMAL Check vs 1/4" (6.3mm) cont depth : NO Wind(runway) : KT Crosswind : KT Altitude type : QNH Pressure altitude : HPA Maximum structural weight : KG Configuration : CONF 1+F Engine option : TOGA Air conditioning : Off Anti-icing : Off CG code : Basic Turn option : NO ACG Check : NO Tflex Max DISA : DEG C - SPECIAL CASES ARE INDICATED WITH A STAR (*) - Reversers credit : ALL REVERSERS INOPERATIVE Antiskid : ON Flight with landing gears extended : NO Braking failed : 0 BRAKE INOPERATIVE Autobrake : OFF Spoilers : ALL SPOILERS OPERATING Ground idle failed : NO Eng A-Ice valve blocked open : NO Hydraulic pump failure : NO Tachometer failure : NO CURRENT RUNWAY NUMBER : 1 Airport identification : LISBOA Runway identification : 17 Airport ICAO code : LPPT Airport IATA code : LIS Airport elevation : FT Runway length representation : TODA - ASDA TORA : M TODA or clearway : M ASDA or stopway : M Alignment allowance selection : STANDARD Alignment allowance for TORA and TODA : M Alignment allowance for ASDA : M Multiplicatif coefficient on ASDA : Additif coefficient on ASDA : M Runway slope : % Runway width : M Runway condition : DRY Number of obstacles to take account : Comment line 1 for take-off : Comment line 2 for take-off : Obstacle reference Obstacle X position Obstacle Y position Obstacle H position END OF TORA M M FT DEGRADATION ON CONSTRAINTS : NO COEFFICIENT ON A/C PERFORMANCE Number of negligible CDL items : CALCULATION NAME : TAKE-OFF OPTIMIZATION 75

88 ABSCISSA CALCULATION I OAT TEMPERATUI MAX WEIGHT I 1ST SEG W I 2ND SEG W I LIM COD1 V1MII I DEG C I KG I KG I KG I I I I I I I 6. I I I I I I 6. I ( ) I I I I I 19. I I I************* I************* I************* I************* I I OAT TEMPERATUI LIM COD2 V1MII LIM COD1 V1MAI LIM COD2 V1MAI LIM COD1 V1BAI I DEG C I I I I I I I 3. I 6. I 3. I 0. I I I 3. I 6. I 3. I 0. I ( ) I I 6. I 19. I 6. I 0. I I I************* I************* I************* I************* I I OAT TEMPERATUI LIM COD2 V1BAI V2/VS I V1/VR MIN I V1/VR MAX I I DEG C I I I I I I I 0. I I I I I I 0. I I I I ( ) I I 0. I I I I I I************* I************* I************* I************* I I OAT TEMPERATUI V1/VR BAL I V1 MIN IAS I V1 MAX IAS I V1 BAL IAS I I DEG C I I KT I KT I KT I I I I I I I I I I I I I ( ) I I I I I I I I************* I************* I************* I************* I 76

89 I OAT TEMPERATUI V2 IAS I VR IAS I TOD1 V1 BAL I TOD1 V1 MIN I I DEG C I KT I KT I M I M I I I I I 0.0 I I I I I I 0.0 I I ( ) I I I I 0.0 I I I I************* I************* I************* I************* I I OAT TEMPERATUI TOD1 V1 MAX I TOR1 V1 BAL I TOR1 V1 MIN I TOR1 V1 MAX I I DEG C I M I M I M I M I I I I 0.0 I I I I I I 0.0 I I I ( ) I I I 0.0 I I I I I************* I************* I************* I************* I I OAT TEMPERATUI ASD V1 BAL I ASD V1 MIN I ASD V1 MAX I 1.15 TOD0 I I DEG C I M I M I M I M I I I 0.0 I I I I I I 0.0 I I I I ( ) I I 0.0 I I I I I I************* I************* I************* I************* I I OAT TEMPERATUI 1.15 TOR0 I GROSS 1ST SEGI GROSS 2ND SEGI GROSS FTO I I DEG C I M I % I % I % I I I I I I I I I I I I I ( ) I I I I I I I I************* I************* I************* I************* I I OAT TEMPERATUI BR ENER V1 MII BR ENER V1 MAI BR ENER V1 BAI OH2MIN I 77

90 I DEG C I % I % I % I FT I I I 75.3 I 75.3 I 0.0 I I I I 75.4 I 75.4 I 0.0 I I ( ) I I 65.1 I 65.1 I 0.0 I I I I************* I************* I************* I************* I I OAT TEMPERATUI OH2MAX I NUM OBST V1MII NUM OBST V1MAI NUM OBST V1BAI I DEG C I FT I I I I I I I 0. I 0. I 0. I I I I 0. I 0. I 0. I ( ) I I I 1. I 1. I 0. I I I************* I************* I************* I************* I I I I I I OAT TEMPERATUI OH2GMINP I OH2GMAXP I I I I I I DEG C I FT I FT I I I I I I I I I I I I I I I I I I I I I ( ) I I I I I I I I I I I I I I************* I************* I I I I I 78

91 c) TLP Takeoff Optimization Output 79

92 d) TLP Landing Optimization Output 80

93 e) Sample Excel File produced during TLP validation 81

94 C2. Visual Basic Classes a) Airport Class 82

95 b) Aircraft Class 83

96 C3. Functions a) tisa 'Returns the standard temperature ( C) at a given altitude (ft) Public Function tisa(byval altitude As Decimal) Dim t_isa As Decimal 'Above MSL and below the tropopause (36,089 feet): ' (Page 70 - Jet Transport Performance Methods, The Boeing Company) Dim T0 As Decimal = 15 '[ C] (standard temperature at sea level) t_isa = T * altitude Return t_isa End Function b) pa2p 'Returns the pressure value (P in hpa) corresponding to the specified pressure 'altitude (PA in ft) Public Function pa2p(byval pa As Decimal) Dim P As Decimal If pa >= 0 Then ' Above MSL and below the tropopause (36,089 feet): ' (Page 18 - Gettin to Grips with AC Performance) Dim P0 As Decimal = '[hpa] (standard pressure at MSL) Dim T0 As Decimal = '[K] (standard temperature MSL) Dim α As Decimal = '[ C/m] Dim g0 As Decimal = '[m/s2] Dim R As Decimal = '[J/kg/K] Dim h As Decimal '[m] (altitude) ' conversion from feet to meters h = pa * P = P0 * (1 - α * h / T0) ^ (g0 / (α * R)) '[hpa] Else 'Below MSL End If Dim a As Decimal = -28 Dim b As Decimal = Return P End Function P = (pa - b) / a c) p2pa 'Returns the pressure altitude value (h in ft) corresponding to the specified pressure (P in hpa) Public Function p2pa(byval P As Decimal) Dim h As Decimal '[m] (altitude) If P >= Then ' Above MSL and below the tropopause (36,089 feet): ' Rearrangement of the formula from: 84

97 ' Page 18 - Gettin to Grips with AC Performance Dim P0 As Decimal = '[hpa] (standard pressure at MSL) Dim T0 As Decimal = '[K] (standard temperature at MSL) Dim α As Decimal = '[ºC/m] Dim g0 As Decimal = '[m/s2] Dim R As Decimal = '[J/kg/K] Dim m2ft As Decimal = 'conversion from meter to feet h = (T0 / α) * (1 - (P / P0) ^ (α * R / g0)) '[m] h = h * m2ft '[ft] Else ' Below MSL End If Dim a As Decimal = -28 Dim b As Decimal = Return h End Function h = a * P + b d) SetInitialTemperatureValues() 'Computes Tref, Tmax and Tflexmax Public Sub SetInitialTemperatureValues( ByVal pressure As Decimal, ByVal pressure_setting As String, ByVal elevation As Decimal, ByVal Aircraft As Plane, ByRef tref As Decimal, ByRef tmax As Decimal, ByRef tflexmax As Decimal ) Dim tflexmax_isa, tflexmax_disa As Decimal Dim altitude_correction, t_correction, pressure_altitude As Decimal If pressure_setting = "QNH" Then 'QNH altitude_correction = BLL.p2pa(pressure) pressure_altitude = elevation + altitude_correction Else 'ZP pressure_altitude = pressure End If End Sub 'Estimate temperature values tref = pressure_altitude * Aircraft.tref_a + Aircraft.tref_b tmax = pressure_altitude * Aircraft.tmax_a + Aircraft.tmax_b tflexmax = pressure_altitude * Aircraft.tflexmax_a + Aircraft.tflexmax_b 'Estimate temperature correction tflexmax_disa = BLL.ParseString2Num(Aircraft.tflex_max_disa) tflexmax_isa = BLL.tISA(elevation) + tflexmax_disa t_correction = tflexmax_isa tflexmax 'Apply correction tref += t_correction tmax += t_correction tflexmax = tflexmax_isa 85

98 APPENDIX D FAJS-21R 86

99 87

100 88

101 89

102 APPENDIX E FM Page - A

103 APPENDIX F Obstacles Limitation Verification The following graphics were obtained in Excel. The corresponding data points were calculated by the Flight Path function of PEP s certified FM module. Position (0,0) corresponds to brake release. 91

104 92

105 93

106 94

107 APPENDIX G PEP-FM Files F1. Complete Takeoff Function OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AB202C02 A /V I INPUT DATA RECAPITULATION I Runway condition : DRY Pressure altitude : FT Runway slope : % Temperature type : OAT Temperature : DEG C Wind(runway) : KT Air conditioning : Off Anti-icing : Off Engine option : TOGA Configuration : CONF 1+F CG code : Basic Weight : KG V1 type : V1/VR V1 : V2 type : V2/VS V2 : SPECIAL CASES ARE INDICATED WITH A STAR (*) - Reversers credit : ALL REVERSERS INOPERATIVE Antiskid : ON Braking failed : 0 BRAKE INOPERATIVE Autobrake : OFF Flight with landing gears extended : NO Spoilers : ALL SPOILERS OPERATING Ground idle failed : NO Eng A-Ice valve blocked open : NO Tachometer failure : NO Number of negligible CDL items : CALCULATION NAME : COMPLETE TAKE-OFF APPROVED if edited or printed by AIRBUS PEP tool POINT CALCULATION AUG-11 I TOD OEI I 1.15 TOD AEO I TOR OEI I 1.15 TOR AEO I ASD OEI I I M I M I M I M I M I I I I I I I I ASD AEO I BRK ENER AEO I BRK ENER OEI I V1 CAS I V1 IAS I 95

108 I M I % I % I KT I KT I I I 99.7 I 93.8 I I I I VR CAS I VR IAS I VLOF0 CAS I VLOF0 IAS I VLOF1 CAS I I KT I KT I KT I KT I KT I I I I I I I I VLOF1 IAS I V2 CAS I V2 IAS I V2/VS I 1ST SEG GRAD I I KT I KT I KT I I % I I I I I I I I I I I 2ND SEG GRAD I N1 I I I I I % I % I I I I I I I I I I CKSUM2 =

109 F2. Landing Distance Function Output OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AB202C02 A /V I INPUT DATA RECAPITULATION I Regulatory multiplication coefficient : Runway condition : SLUSH 1/4" Pressure altitude : FT Wind(runway) : KT Configuration : CONF FULL CG code : Basic Weight : KG Engine option : NO BUMP k(v/vs) : Delta V (CAS) : KT - SPECIAL CASES ARE INDICATED WITH A STAR (*) - Reversers credit *: ALL REVERSERS INOPERATIVE Antiskid : ON Braking failed : 0 BRAKE INOPERATIVE Spoilers : ALL SPOILERS OPERATING Ground idle failed : NO Tachometer failure : NO Number of negligible CDL items : CALCULATION NAME : LANDING DISTANCE APPROVED if edited or printed by AIRBUS PEP tool POINT CALCULATION AUG-11 I LD I REGUL COEF I REQUIRED LD I FACTORED LD I VFA CAS I I M I I M I M I KT I I I I I************* I I I VFA IAS I BRK ENER AEO I VREF CAS I DELTA VREF I FAILURE LD I I KT I % I KT I KT I M I I I 36.2 I************* I************* I************* I I I I I FAILURE COEF I FAILURE BRK EI I I I I I % I I I I I************* I************* I I I I CKSUM2 =

110 F3. Operational Landing Distance Function Output OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AB202C02 A /V I INPUT DATA RECAPITULATION I Runway condition : SLUSH 1/4" Pressure altitude : FT Wind(runway) : KT Configuration : CONF FULL CG code : Basic Brake mode : LOW Weight : KG Engine option : NO BUMP k(v/vs) : Delta V (CAS) : KT Autoland : NO - SPECIAL CASES ARE INDICATED WITH A STAR (*) - Reversers credit *: ALL REVERSERS INOPERATIVE Number of negligible CDL items : POINT CALCULATION CALCULATION NAME : OPERATIONAL LANDING DISTANCE FOR INFORMATION ONLY 29-AUG-11 I AIRBORNE DISTI GROUND DIST I ACTUAL LD I VFA CAS I VFA IAS I I M I M I M I KT I KT I I I I I I I I BRK ENER AEO I VREF CAS I DELTA VREF I FAILURE LD I FAILURE COEF I I % I KT I KT I M I I I 31.8 I************* I************* I************* I************* I I I I FAILURE BRK EI I I I % I I I I************* I I I CKSUM2 =

111 F4. Landing Climb Gradient Function Output OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AB202C02 A /V I INPUT DATA RECAPITULATION I Weight or gradient calculation : WEIGHT CALCULATION Gradient calculation option : NORMAL Gradient : % Temperature type : OAT Temperature : DEG C Pressure altitude : FT Air conditioning : Off Anti-icing : Off Configuration : CONF FULL CG code : Basic Engine option : NO BUMP - SPECIAL CASES ARE INDICATED WITH A STAR (*) - Eng A-Ice valve blocked open : NO Number of negligible CDL items : CALCULATION NAME : LANDING CLIMB GRADIENT APPROVED if edited or printed by AIRBUS PEP tool 29-AUG-11 POINT CALCULATION I WEIGHT I LCG I W REGUL LCG I REGUL LCG I SPEED (CAS) I I KG I % I KG I % I KT I I I I************* I I I I I I I I SPEED (IAS) I REG SP (CAS) I REG SP (IAS) I I I I I I KT I KT I KT I I I I I I I************* I************* I I I I I CKSUM2 =

112 F5. Approach Climb Gradient Function Output OCTOPUS VERSION : REGULATION NAME : JAA AIRCRAFT NAME : AB202C02 A /V I INPUT DATA RECAPITULATION I Gradient calculation option : NORMAL Weight or gradient calculation : WEIGHT CALCULATION Gradient : % Type of approach climb : CATEGORY 2 APPROACH Temperature type : OAT Temperature : DEG C Pressure altitude : FT Air conditioning : Off Anti-icing : Off Configuration : CONF 3 CG code : Basic Engine option : NO BUMP - SPECIAL CASES ARE INDICATED WITH A STAR (*) - Eng A-Ice valve blocked open : NO Flight with landing gears extended : NO Number of negligible CDL items : CALCULATION NAME : APPROACH CLIMB GRADIENT APPROVED if edited or printed by AIRBUS PEP tool 29-AUG-11 POINT CALCULATION I WEIGHT I ACG I W REGUL ACG I REGUL ACG I SPEED (CAS) I I KG I % I KG I % I KT I I I I************* I I I I I I I I SPEED (IAS) I REG SP (CAS) I REG SP (IAS) I I I I I I KT I KT I KT I I I I I I I************* I************* I I I I I CKSUM2 =