Use of RNAV (GNSS) for Non Precision Approach. Paul Willis, Managing Partner, Cyrrus Associates, Dr. E. Matsoukis, Assoc. Prof., University of Patras, and S. Poulimenakos, Air Traffic Controller. 1 Introduction. The use of RNAV (GNSS) as an alternative to traditional ground based radio navigational guidance is an exciting development within the aviation and airline industry. The use RNAV represents a significant development towards the use of GNSS technologies as a replacement to traditional ILS / MLS precision approaches. Although the use of GNSS for precision approach has still to be accepted by the International community for many reasons, the likely date being not until the year 2015. However, the use of RNAV for non-precision approaches still represents an important milestone in the transition from traditional navigational techniques to satellite based technology. The use of RNAV for non-precision approaches has significant benefits as it provides a cost effective navigation solution to runways that have no traditional navigational infrastructure. 2 What is RNAV GNSS. RNAV GNSS non-precision approach techniques make use of Global Positioning Satellites (GPS) to determine the aircrafts position on the final approach to an airport. RNAV / GNSS procedures are predicted on continuous descent approach (CDA) rather than stepped descent. This offers environmental advantages in addition to reduced pilot workload together with a stabilised approach with associated safety benefits. 3 Operational Considerations. A non - precision approach traditionally uses a ground based navigation facility providing the aircraft with a bearing and distance to a fixed point, usually on the airport. The aircraft uses this guidance information along with a published procedure (national AIP and / or Jeppeson) to fly to an altitude on the approach to the airport, this will normally be to a minimum decision height (MDH) of between 300ft 400ft. This is however dependent on the surrounding terrain. This type of approach is reliant on ground base infrastructure being available and to an acceptable signal quality to provide aircraft guidance within a declared tolerance.
The use of RNAV for non-precision approach requires an aircraft to be fitted with a GNSS airborne receiver that is certified to FAA TSO C129a Class A1 (standalone) standards or B1/B3 for Flight Management System (FMS) integrated equipment. RNAV (GNSS) approach mode can only be selected when using a certified (ie Jeppeson) database. It is not possible to use manually inputted waypoints, except for flight inspection. The tolerances applied to an aircraft making a NPA are an alarm limit of 550m, with 10 seconds to alarm at the declared MDH. GNSS position fixing will achieve a horizontal position accuracy of 100m of 0.05NM with a 95% probability. Compare this with a Non Directional Beacon that has a bearing uncertainty of 5 degrees, this equates to a horizontal error of +/- 0.5NM at a range of 6NM. It should be noted that the position error of GNSS is uniform where a ground based navigational facility achieves greater accuracy as the aircraft approaches the beacon. 4 Considerations. In order for RNAV GNSS non-precision approaches to be Internationally acceptably to the aviation industry more investigation and analysis is still required by manufactures, airlines, national regulators and technical institutions. One of the main problems is that RNAV equipment contains proprietary algorithms and therefore there is insufficient data available at present to validate target levels of safety. Furthermore database integrity is a further problem that has not been sufficiently addressed to the satisfaction of many national regulatory authorities. In addition RNAV/GNSS NPA does not form part of a pilots instrument rating training and testing in most (if any) countries. Training and testing is the responsibility of the operator. This will probably change as GNSS NPA becomes more widely accepted. Most pilots have heard of it, but very few have done it. 5 Future Activities. Cyrrus Associates with Flight Precision has recently developed a RNAV NPA procedure for a UK Civil Airport. This procedure will be published within the UK AIP and has been subject to rigorous review by the UK CAA Safety Regulation Group. Having published the procedure, Cyrrus Associates along with their partner Flight Precision will conduct regular flight tests and gather flight data to evaluate the published procedure. This will enable further analysis and investigation to be carried out with the goal to develop additional IFR procedures using GNSS in the future.
RNAV (GNSS) for Non Precision Approach By Paul Willis Cyrrus Associates & Sarandis Poulimenakos University of Patra
Overview What is BRAV Operational Considerations Cost benefits & advantages Constraints Next Steps
VELOP 1J 38 10'10" N 023 44'08" E 38 10'10" N 024 33'20" E ASTOV 37 25'03" N 022 32'06" E PIKAD 38 03'47" N 022 41'57" E NEMES 37 42'05" N 022 34'43" E ASTOV 1J 33 R 261 DDM 13 RILIN 1J PIKAD 1J 14 9000 FT 303 277 KORINTHOS NDB 392 KOR * 37 55'56.14" N 022 55'57.82" E Area Navigation 023 25'25.81" E NEMES 1J 33 R 292 DDM SAT VOR / DME 109.6 SAT 37 55'00.48" N 023 54'51.84" E 745 NOTE 2 Traditional Area Navigation is based on. VOR / DME or NDB ground based radio beacons. EGN The VOR/DME and / or NDB provides the aircraft with a guidance signal that allows navigation by means of flying a bearing or radial to fixed point. This SUNis normally to the overhead of the ground radio beacon. These beacons are positioned so that an aircraft KEA can DIDIMON fly declared VOR/ routes DME 117.2 within the national airspace. 20 R 168 DDM RILIN 1J PIKAD 1J 35 R 271 ATH DDM * 37 28'40.08" N 023 13'01.77" E ATHINAI VOR / DME 114.4 ATH * 37 54'03.15" N ABLON R ASTOV 1J R 221 ATH NEMES 1J VELOP 1J An example of this is the Standard Instrument 35 NOTES: Departure for 03R Spata Airport. 16 KVR 6000 FT 1100 FT R 048 SAT SPA 1. THE RESTRICTION IN CLIMB TO A MAXIMUM ALTITUDE ( E.G. 6000 ft ) IS APPLIED IN CASE OF RADAR FAILURE AND IF NOT OTHERWISE INSTRUCTED BY ATC. 2. RADAR ANTENNA TOWER AT 745 FT ( 227 M ) LOCATED 1400 M TO THE EAST OF 21 L THRESHOLD. R 266 KRO KEA VOR / DME 115.0 * 37 33'26.13" N 024 17'55.99" E 4 0 0 0 FT 6000 FT 0 0 0 6 FT D M E 5 K R O 5000 FT 6000 FT SOREV 1J 6000 FT R 013 KRO NEVRA 1J 11 R 027 KRO SOREV 1J 28 R 165 KEA SCALE 1:650'000 VELOP NM 0 KM 0 5 5 10 10 15 20 BADEL
Area Navigation What is RNAV? BRNAV is B asic A rea Navigation. Makes use of Global Position Satellites (GPS) to determine the aircrafts position in 3 dimensions (x,y,z). If way points gave been predetermined then an aircraft track can be established enabling the aircraft to navigate between any 2 fixed points.
Area Navigation Way Point 1 Intermediate Fix Intermediate Fix RNAV aircraft position fixing, showing an aircraft navigating between two Way Points Way Point 2
Operational Constraints Airborne GNSS Receiver. Aircraft Receiver has to be certified to FAA TSO C129a Class A1 (standalone) or B1/B3 for Flight Management System (FMS) integrated equipment. RNAV (GNSS) approach mode can only be selected when using a certified (Jeppeson) database.
Area Navigation Traditional Area Navigation is based on. VOR / DME or NDB ground based radio beacons. The VOR/DME and / or NDB provides the aircraft with a guidance signal that allows navigation by means of flying a bearing or radial to fixed point. This is normally to the overhead of the ground radio beacon. These beacons are positioned so that an aircraft can fly declared routes within the national airspace.
Position Accuracy (Radio Beacon) Accuracy Requirements (NDB). 0.5nm Range 6 nm NDB Beacon Assuming the NDB has a bearing error of +/- 5 degrees. At 6nm this equals a horizontal error of 0.5NM.
Position Accuracy RNAV Accuracy Requirements (RNAV). Position Error Boundary 95% Probability 100m Aircraft track Position accuracy factor of 10 times better than NDB at 6NM.
Cost Benefits & Advantages RNAV is not reliant on any ground infrastructure, this is of particular benefit to those airports that operate without any navigational facilities on one or both runways. Given the challenging terrain and number of airports in Greece RNAV Non Precision Approach can offer real benefits to the airline operator, approach minima of 300-400 ft. In the future both Standard Instrument Departures and Arrivals can be based on RNAV making better use of airspace. Design missed approaches using RNAV, shorter routings, therefore greater fuel savings.
54 40'N 400 293 001 40'W 001 30'W 001 20'W 001 10'W MNM SECT ALT 293-088 SPA VOR 6000-25 NM GP/DME 111.10 NVN11 I-ATR ATHINAI CH 480X VOR/DME 114.4 54 40'50.00" 37 55'40.08" N N Cost Benefits ATH & Advantages 023 56'56.40" E * 37 54'03.15" N 023 43'42.76" E LLZ 111.10 10 NM IAWP1 001 19'09.03" W ATHINAI 161 NVE11 54 37'58.44" N 001 11'49.89" W 232 KRO 54 40'N IAWP2 NVE13 54 39'19.09" N 001 09'17.97" W MNM SECT ALT 206-293 SPA VOR 4500-25 NM NVW04 RNAV Non 54 31'13.19" Precision N Approach Procedures IWP are 54 36'02.69" N designed on a continuous decent approach AIGINA 001 15'27.46" W Firstly lets look at a traditional ILS This has Environmental benefits 023 25'25.81" E FAF Instrument Approach (less noise). 9 DME I - ATR 37 48'20.30" MAX NIAS 023 49'54.75" E 210 KT 54 30'N D408 / 2.5 OCNL / 5.6 (CDA) NDB 382 KVR EGN rather than a traditional stepped MNM SECT descent. IAWP3 ALT * 37 45'51.06" N 12 NM EGN 118 IF 2500 FT 19 DME I - ATR SUN54 31'18.67" N Now for a RNAV approach. BEARINGS ARE MAGNETIC KEA 37 40'19.00" N 001 24'21.34" W 023 42'21.70" E Reduced Pilot ALTITUDE AND ELEVATIONS workload VOR/DME 115.0during final R 062 DDM 25 NM NVW06 DDM approach. * 37 28'40.08" N 54 26'17.68" N NM 0 1 2 3 4 5 PERES LEEMING CMATZ KM 0 1 2 3 4 5 6 7 8 9 10 D409 / 3.4 30 DME ATH Stabilised 37 24'13.36" N approach & Safety 127.750 54 20'N 023 39'10.74" E benefits. DDM 13 DME DDM VOR/DME 5000 FT PERES EGN NDB DIDIMON VOR/DME 117.20 ILS RDH 54.1 FT 023 13'01.77" E 400 R 185 ATH 15 NM 001 32'41.68" W R 220 SPA 034 052 4000 FT 4000 FT TRANSITION ALTITUDE 9000 FT MNM ALT 001 33'43.43" W 034 IF 19 DME I - ATR 03L SAT 232 ARE IN FEET DISTANCES ARE IN NM LATITUDE AND LONGITUDE 0 NM IN WGS 84 KM FAWP NVE04 03R 54 33'20.30" N 001 20'32.52" W 0 1 3200 FT SCALE 1:350'000 KEA * 37 33'26.13" N 1 2 3 4 5 024 17'55.99" E FAF 9 DME I - ATR SCALE 1:500'000 SPA VOR / DME 35 30 25 20 15 10 5 0 NM 5 10 15 2 GP 3 034 5 DME I - ATR 1917 FT R 331 KEA 26 NM 3 DME I - ATR R 197 KEA MNM ALT 5000 FT MISSED APPROACH: Climb straight ahead. At 3 DME (passed the station) I - ATR turn right. Intercept R 331 KEA, proceed to KEA VOR/DME and hold. Climb to 5000 FT, climb gradient 3 % until passing 1200 FT. (SEE NOTE) Nautical Miles from THR (THR RWY 03 R) ELEV 271 FT (THR RWY 03 R) 3 10 NM 4 MAWP NVE01 SPA VOR/DME 117.5 SPA 37 55'04.80" N 023 56'16.80" E 5 6 7 8 9 001 40'W 001 30'W 001 20'W 001 10'W 10 232 700 NVN08 400 1000 304 088 088 - NVE12 206 SPA VOR 3500-25 NM 54 33'28.05" N 001 07'33.99" W 400 54 30'N 1300 54 20'N
Constraints All survey data, terrain, runways, reference datums and obstacle data must be surveyed to the International standard WGS-84. This has not yet been completed in Greece. RNAV GNNS Receivers contain proprietary software & algorithms. Greater analysis by manufactures and technical institutions is still required to ensure that Target Levels of Safety are achieved (better than 1x10-7 ) RNAV is reliant on the aircraft s certified data base, proving the integrity of the database to the national regulator maybe difficult. RNAV NPA does not form part of a pilots instrument rating in many countries.
Next Steps Cyrrus Associates along with their strategic partner Flight Precision has designed the first published RNAV Non Precision Approach in the United Kingdom. Flight Precision, being the UK licensed flight inspector will undertake pilot training and extensive flight inspection of the promulgated procedure to gather more data for future analysis & validation. With the UK regulator develop procedures and methods to enable additional IFR procedures to developed using RNAV principals. Participate with industry and technical institutions to develop robust safety analysis and validation of aircraft equipment.