Autonomous Taxiing Evaluation of an Autonomous Taxi Solution for Airport Operations during Low Visibility Conditions Frank Bussink (NLR) Ninth USA/Europe Air Traffic Management Research and Development Seminar (ATM2011) Berlin June 16, 2011 Nationaal Lucht- en Ruimtevaartlaboratorium National Aerospace Laboratory NLR
Overview Introduction Autonomous Taxi Concept Experiment Results Conclusions 2
Introduction Airport Operations Ground Control Ground Controller (GC) in Aerodrome Control Tower Controls traffic at Manoeuvring Area Provides information and clearances Performs surveillance tasks based on outside view 3
Introduction Airport Operations during Low Visibility Conditions Low Visibility Procedures apply Protection of ILS sensitive area Decreased landing capacity Limited use of taxiways Increase in workload of GC Limited outside view Support systems (radar) Active control of traffic Decrease of taxi speed => Capacity drops during Low Visibility Conditions (LVC) 4
Introduction Airport capacity Amsterdam Airport Schiphol 5
Introduction Objective Investigate whether autonomous taxiing might be a solution to increase airport capacity during Low Visibility Conditions Autonomous Taxiing Transfer tasks from ATC to flight crew Flight crews have to operate (more) independent of ATC Flight crews have better outside view of their own situation Flight crew workload increases A means to improve airport capacity...? ATC = Air Traffic Control 6
Autonomous Taxi Concept 7
Concept Autonomous Taxi Concept Distant future concept No Air Traffic Control Building on current and near future developments ADS-B / ASAS taxi displays data link... Taxi clearance Contains only destination Taxi phase Flight crew taxies from gate to runway or v.v. Pilot-Flying (PF) operates aircraft Pilot-Non-Flying (PNF) performs certain ATC tasks 8
Concept Flight Crew tasks Tasks during taxi phase 1. Control of the aircraft 2. Position awareness 3. Navigation 4. Conflict detection 5. Conflict resolution 9
Concept Flight Crew support Taxi display Airport Moving Map (AMM) Digital airport map Ownship position =>Providing position awareness 10
Concept Flight Crew support Add to taxi display: Routing functionality Creating taxi routes Depicting taxi route on AMM => Navigation support Cockpit Display of Traffic Information (CDTI) ATSA-SURF Conflict Detection & Alerting (CD&A) functionality Detecting conflicts Providing alerts 11
Concept Taxi display design First evaluation of autonomous taxiing Focus on taxi phase Can flight crews taxi (efficiently) without ATC support? Taxi display is proven aid for navigation Focus on Conflict Detection and Resolution Can flight crews deal (efficiently) with traffic conflicts? Evaluate multiple levels of autonomy + support ATC or flight crew responsible for conflict detection and resolution Three levels of support on taxi display 12
Concept Taxi display: autonomy level 0 No autonomy: baseline, based on current day situation ATC responsible for CD&R ATC can be contacted Taxi display Integrated in Navigation Display Airport Moving Map (AMM) Depiction of taxi clearance No ADS-B traffic 13
Concept Taxi display: autonomy level 1 Autonomy Flight crew responsible for CD&R ATC can NOT be contacted Taxi display Taxi display autonomy level 0 Cockpit Display of Traffic Information Position (ADS-B) Identification Groundspeed 14
Concept Taxi display: autonomy level 2 Autonomy Flight crew responsible for CD&R ATC can NOT be contacted Taxi display Taxi display autonomy level 1 Conflict alerting algorithm 15
Concept Taxi display: autonomy level 2 Conflict alerting algorithm Closest Point of Approach (CPA) Based on state-vector Heading Groundspeed Conflict definition: t CPA < 60 sec Protected Zones overlap each other t CPA determines severity 16
Concept Taxi display: autonomy level 2 Alert Level 1 Proximity < 150 m Conflict < 60 sec Traffic symbol = yellow 17
Concept Taxi display: autonomy level 2 Alert Level 1 Proximity < 150 m Conflict < 60 sec Traffic symbol = yellow Alert Level 2 Conflict < 30 sec Traffic symbol = amber Aural beep 18
Concept Taxi display: autonomy level 2 Alert Level 1 Proximity < 150 m Conflict < 60 sec Traffic symbol = yellow Alert Level 2 Conflict < 30 sec Traffic symbol = amber Aural beep Alert Level 3 Conflict < 10 sec Traffic symbol = Red Aural TRAFFIC Text TRAFFIC on PFD 19
Experiment 20
Experiment Experiment Design Evaluation of the full autonomy concept Focus on resolution of conflicts 10 professional airline pilots GRACE civil flight simulator 21
Experiment Experiment Matrix Three autonomy levels Two low visibility conditions 400m RVR 150m RVR Experiment Scenario Taxi-run at Schiphol of ± 10 minutes (12 x) Flight crew ready to taxi Taxi clearance uplinked via data link A number of conflicts occur that should be solved Based on ICAO Rules of the Air 22
Experiment Experiment Measurements FaceLAB Objective data Aircraft performance Pilot inputs Facelab eye tracking Subjective data NASA-TLX (workload) SART-10D (Situational Awareness) Questionnaires Pre-experiment After-run questionnaires After-experiment questionnaires 23
Results 24
Results Overview Safety Efficiency Acceptability 25
Results Safety (objective): conflict anticipation Situations where ownship has to give way Flight crew responsible (autonomy level 1 and 2) => Reveals effect of conflict alerting 26
Results Safety (objective): conflict anticipation Effect of conflict alerting Lower reaction times (non significant) 13,7 seconds for autonomy 1 10,9 seconds for autonomy 2 Conflict start Alerting triggers reaction Alert Level 3 occurrence Autonomy 1: 20% Autonomy 2: 0% With alerting on, larger separation margins (especially during 150 m RVR) 27
Results Safety (objective): Head-down time Facelab Eye tracking data Significantly more head down during autonomy 1 and 2 Situations require flight crew to monitor traffic (with use of taxi display) Pilot role No effect of visibility condition Clear difference between pilot role during autonomy 1 and 2 PNF is more head down PNF monitors traffic on taxi display in support of PF 28
Results Safety (subjective): Situational Awareness (SA) SART-10D method SA increases with autonomy level and better visibility Situational awareness Positive effect of taxi display 29
Results Safety (subjective): Questionnaires Practically all conditions were experienced as safe Alerting improves safety Better visibility = safer During autonomy 0, safety depends completely on ATC 30
Results Efficiency (Objective): Unforced stops Ideal situation: no stopping Preferably adjusting speed From 25 right of way situations: 10 times slowing down (40%) 4 stops (16%) Reason stated: Missing information about other aircraft intentions and clearances 31
Results Efficiency (Subjective): Questionnaires Taxi display improves efficiency Especially taxi route information makes taxiing easy Lack of ATC has negative impact on efficiency Missing party-line effect (R/T) No information about other aircrafts intentions 32
Results Acceptability (subjective): Workload NASA-TLX method: No clear effect of autonomy NASA-TLX Significant difference for visibility 33
Results Acceptability (subjective): Questionnaires Better visibility rated as more acceptable Autonomy 0: acceptable - very acceptable (4.2) Extension to current day situation Autonomy 1: slightly acceptable - acceptable (3.8) Increase of workload due to CD&R task and unknown intentions of other aircraft stated (not confirmed by NASA TLX scores) Autonomy 2: slightly acceptable acceptable (3.9) Conflict alerting slightly compensates for workload 0-5 rating scale 34
Conclusions 35
Conclusions Research objective Investigate whether autonomous taxiing might be a solution to increase airport capacity during Low Visibility Conditions No incidents occurred Flight crew able to monitor conflicts in time and look for a safe resolution Each level of the taxi display is helpful Improves navigation and Situational Awareness, so safety Alerting function has a positive influence on conflict anticipation 36
Conclusions Continued Unwanted stops do not improve airport capacity Expensive and time-consuming Lack of information currently provided by ATC makes autonomous taxiing less safe, acceptable and efficient Lack of information about other aircraft intentions No backup option (essential during LVC) Provision of taxi display with traffic and alerting information might already decrease GC workload in current day operations 37
Conclusions Recommendations Improve taxi display support: Provide intentions of concerned aircraft Future path information (Virtual) stopbars Aircraft priority indicators Conformance monitoring Route deviations Runway Incursions Include digital NOTAMs 38
Conclusions Recommendations continued Improve concept: Conflict Detection & Resolution Detection algorithm Conflict resolution Routing Sequencing Timing (4D) 39
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