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Piloted Simulation of NextGen Time-based
 Taxi Clearances and Tailored Departures

                 David C. Foyle, PhD
  ...
Outline

• S f
  Surface operations
                 ti
• 4-D (time-based) taxi clearances
• Surface Traffic Management (S...
Surface Operations
•   Airport surface congestion results in the largest delay cost in US
       p               g        ...
Pilot Requirements for 4D Taxi Clearances

                                          Problem: Integrating surface
        ...
Development of Time-based STMs
           (Surface Traffic Management (STM) Systems)

Defining Characteristics
• ATC/STM -...
Development of Time-based STMs
           (Surface Traffic Management (STM) Systems)

Defining Characteristics
• ATC/STM -...
Taxi-out Departure
Taxi-out Departure




“Departure is currently the highest
workload phase of flight”
                   - Richard L Newman...
Simulation


Medium Fidelity Part-task Simulator
                 Part-
• Human-Centered Systems
  Human-
   Laboratory (H...
Experiment Overview

Pilot Tasks
• Taxi (with speed/time)
• Verify departure clearance
• Maintain checklist
• Traffic sepa...
DFW Routes

12 Unique DFW Routes
• 14,300’ length (avg.)
• Repeated 2x
 - Different traffic flow points
 - Other traffic  ...
NextGen Conditions and Displays
                                   Primary Flight Display (
                              ...
NextGen Conditions and Displays
                                      Primary Flight Display (
                           ...
NextGen Conditions and Displays

Limited NextGen
• ATC: Speed commands at traffic
flow points
            Error-nulling
  ...
Checklist, Datalink, Nav Display
                             Taxi Navigation Display (TND)
                              ...
Departure Clearance Verification Task
        NOMINAL
Pending
• Departure clearance sent 25-
75% into route
• Chi
  Chime,...
Departure Clearance Verification Task
         NOMINAL
Pending
• Departure clearance sent 25-
75% into route
• Chi
  Chime...
Departure Clearance Verification Task
     OFF-NOMINAL
2 Mismatch Trials
• 1st – ID number and route
direction
• 2 d – ID ...
Departure Clearance Verification Task
     OFF-NOMINAL
2 Mismatch Trials
• 1st – ID number and route
direction
• 2 d – ID ...
Time of Arrival (TOA) Error
                      TOA error calculation
                      • Actual TOA - Required TOA ...
TOA Error Distributions

TOA error distribution results

Advanced NextGen (error-nulling avionics) much
less variable TOA ...
Departure Clearance Verification Errors




Departure clearance verification results
Incorrect rejections: 3 / 400 nominal...
Departure Clearance Verification Latency

Limited NextGen vs. Advanced
   NextGen (interaction, p=.005)
                  ...
Departure Clearance Verification Latency

Limited NextGen – Speed commands                                                ...
Departure Clearance Verification Latency

Compared to “current-day” baseline
    taxi,
Advanced NextGen (error-nulling
   ...
Post-study Questions

How many ‘speed changes’ (Limited
     NextGen) or ‘traffic flow points’
     (Advanced NextGen) per...
Post-Study Structured Interviews
1.5 hr Post-study Structured Interview Findings

Time-based Taxi Clearances
•   Improve a...
Conclusions
Commanded Speed
•   TOA compliance most accurate with moderate taxi
     - Arrive early for slower speeds; Lat...
Piloted Simulation of NextGen Time-based
 Taxi Clearances and Tailored Departures

                 David C. Foyle, PhD
  ...
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Airport Taxi/Departure Simulation

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This presentation describes the results of a medium fidelity
piloted flight deck simulation of future surface operations.

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Airport Taxi/Departure Simulation

  1. 1. Piloted Simulation of NextGen Time-based Taxi Clearances and Tailored Departures David C. Foyle, PhD NASA Ames Research Center Becky L. Hooey, MSc C st a Christina L. Kunkle, BA u e, Martin F.J. Schwirzke, MA Deborah L. Bakowski, MA San Jose State University Foundation at NASA Ames Research Center ICNS 2009 http://humansystems.arc.nasa.gov/groups/HCSL/
  2. 2. Outline • S f Surface operations ti • 4-D (time-based) taxi clearances • Surface Traffic Management (STM) system characteristics • Simulation Experiment • Results • Conclusions
  3. 3. Surface Operations • Airport surface congestion results in the largest delay cost in US p g g y airspace system (Glass & Gawdiak, 1997) • Delays are caused by competition for resources Solutions • Increase taxi efficiency and improve runway coordination (Cheng, Sharma, & Foyle, 2001) • Coordinated runway crossings can potentially increase traffic throughput of airports (Cheng, Sharma, & Foyle, 2001; Hooey, 2005) • Surface Traffic Management Systems (STMs) – Utilize dynamic algorithms – Precise surface coordination – 4-D (time-based) taxi clearances
  4. 4. Pilot Requirements for 4D Taxi Clearances Problem: Integrating surface traffic management system 4D taxi clearances with flight deck information requirements Advanced surface traffic management systems and ConOps must incorporate pilot Human factors pilot-in-the-loop studies to operating requirements determine pilot operating requirements - Ability to comply with speed requests - Speed conformance - A/C variance of route and time conformance - Route and time conformance - Conceptual development (e.g., form of taxi (e g - Conceptual (ConOps) development clearances - continuous, updates, etc.) - Pilot workload, Situation awareness (SA) - Pilot/Aircraft non-conformance - Safety impacts due to time pressure - Rerouting 4D Taxi Navigation Issues 4D Concepts - Continuous-coupled 4D commands - Progressive taxi/route updates - Endpoint-only 4D commands (push-back, departure queue) 4D Taxi Clearance Display Formats - Speed vs. time displays - C ti Continuous vs. non-continuous command displays ti d di l - Bandwidth of command updates (pilot display and ATC concept) Pilot Performance Metrics - Variance of speed, time-of-arrival error - SA, workload impacts
  5. 5. Development of Time-based STMs (Surface Traffic Management (STM) Systems) Defining Characteristics • ATC/STM - Number of Traffic Flow Points • ATC/STM - Flow Point Time Constraint • ATC/STM - Refresh/reoptimization (due to traffic changes, pilot performance) • Flight Deck - Onboard "display" algorithms (e g error nulling) display (e.g., • Flight Deck - Display Bandwidth Speed (bounding conditions) • Speed (bounding conditions) STM Pilot A/C Algorithms Performance
  6. 6. Development of Time-based STMs (Surface Traffic Management (STM) Systems) Defining Characteristics • ATC/STM - Number of Traffic Flow Points • ATC/STM - Flow Point Time Constraint • ATC/STM - Refresh/reoptimization (due to traffic changes, pilot performance) • Flight Deck - Onboard "display" algorithms (e g error nulling) display (e.g., • Flight Deck - Display Bandwidth Speed (bounding conditions) • Speed (bounding conditions) STM Pilot A/C Algorithms Performance
  7. 7. Taxi-out Departure
  8. 8. Taxi-out Departure “Departure is currently the highest workload phase of flight” - Richard L Newman Phd L. Newman, Formerly FAA Human Factors Specialist, Commercial Transport p NextGen Operations - Dynamic, Tightly Coupled - Potential for High Workload & Errors
  9. 9. Simulation Medium Fidelity Part-task Simulator Part- • Human-Centered Systems Human- Laboratory (HCSL) L b t • NASA Ames Research Center • Previously validated Dallas- Dallas-Fort Worth (DFW) airport Visibility: Clear, distant haze Simple B737 aircraft model Controls: Tiller, throttle, toe brakes, rudder pedals Pilots: 16 commercial transport Age: 25-63 yrs (M=45 5 yrs) 25- (M=45.5 Flight hours: 1,000-20,000 (M=5,586) 1,000-
  10. 10. Experiment Overview Pilot Tasks • Taxi (with speed/time) • Verify departure clearance • Maintain checklist • Traffic separation Traffic Flow Points Independent Variables Limited NextGen: • N tG Implementation (between) NextGen I l t ti (b t ) Speed Change S C - Limited, Advanced Advanced NextGen: • Traffic Flow Points (within) Speed Change & - 1, 3, or 5 • Ta i Speeds (within) Taxi ( ithin) TND Checkpoint - 10, 14, 18, 22 kts Same traffic locations and speeds for Limited NextGen vs. Advanced NextGen conditions Final Dependent Measures Departure • Time of Arrival (TOA) error (at traffic flow points & RWY) Clearance • Departure Clearance Verification (Errors and Latency)
  11. 11. DFW Routes 12 Unique DFW Routes • 14,300’ length (avg.) • Repeated 2x - Different traffic flow points - Other traffic Traffic Flow Points • Final Departure Clearance p given 25-75% into route Trials • 4 Familiarization trials (no data collection, ~1 hr) collection 1 • 24 NextGen nominal Final • 2 Departure clearance Departure mismatches Clearance • 1 “Current-day” taxi
  12. 12. NextGen Conditions and Displays Primary Flight Display ( y g p y (PFD) ) Taxi Navigation Display (TND) g p y( ) Limited NextGen • ATC: Speed commands at traffic flow points • Pilots: Maintain commanded speed (avg.) – 15 kts turn max. • PFD: Current, commanded speed • TND: Route, Traffic
  13. 13. NextGen Conditions and Displays Primary Flight Display ( y g p y (PFD) ) Taxi Navigation Display (TND) g p y( ) Limited NextGen • ATC: Speed commands at traffic flow points • Pilots: Maintain commanded speed (avg.) – 15 kts turn • PFD: Current, commanded speed • TND: Route, Traffic Advanced NextGen • ATC: Speed commands at traffic flow points • Pilots: Maintain commanded speed (dynamic) – 15 kts turn • PFD: Current, commanded speed, Required Time of Arrival (RTA), Elapsed Time, Error-nulling algorithm (for RTA) • TND: Route, Traffic, Traffic flow point
  14. 14. NextGen Conditions and Displays Limited NextGen • ATC: Speed commands at traffic flow points Error-nulling Error nulling algorithm (for RTA): • Pilots: Maintain commanded speed (avg.) – 15 kts turn max. • PFD: Current, commanded speed Remaining Distance g Current commanded speed = C • TND: Route, Traffic Remaining Time Advanced NextGen • ATC: Speed commands at traffic flow points • Pilots: Maintain commanded speed (dynamic) – 15 kts turn • PFD: Current, commanded speed, Required Time of Arrival (RTA), Elapsed Time, Error-nulling algorithm (for RTA) • TND: Route, Traffic, Traffic flow point
  15. 15. Checklist, Datalink, Nav Display Taxi Navigation Display (TND) Datalink Text Pre-trial • TND overview mode Departure Clearance Window • At DFW ramp spot • ATC verbal route clearance Checklist Window • Navigation Display (ND): Pre- loaded predeparture clearance Navigation Di l N i ti Display (ND) • Pilot: “Ready to taxi” Taxi trial • TND: Track-up, perspective • Checklist scan task (~2 min) • Datalink text departure clearance: Predeparture clearance • Navigation Display (ND): Pre- loaded predeparture clearance
  16. 16. Departure Clearance Verification Task NOMINAL Pending • Departure clearance sent 25- 75% into route • Chi Chime, ACCEPT/REJECT flashing • Pilot must verify match between: 1) D t li k t t and Datalink text, d 2) ND - Route ID number - Last leg direction
  17. 17. Departure Clearance Verification Task NOMINAL Pending • Departure clearance sent 25- 75% into route • Chi Chime, ACCEPT/REJECT flashing • Pilot must verify match between: 1) D t li k t t and Datalink text, d 2) ND - Route ID number - Last leg direction Accepted • Accept or Reject clearance (button press) • Loads into FMS/ND • If incorrectly rejected, ATC re-sent
  18. 18. Departure Clearance Verification Task OFF-NOMINAL 2 Mismatch Trials • 1st – ID number and route direction • 2 d – ID number 2nd b • If incorrectly accepted – loaded • If correctly rejected – correct clearance sent
  19. 19. Departure Clearance Verification Task OFF-NOMINAL 2 Mismatch Trials • 1st – ID number and route direction • 2 d – ID number 2nd b Rejected • If incorrectly accepted – loaded • If correctly rejected – correct clearance sent
  20. 20. Time of Arrival (TOA) Error TOA error calculation • Actual TOA - Required TOA (RTA) p=.001 • Limited NextGen: No explicit RTA (Calculated using segment length and ATC-commanded speed) Late TOA error results Early 1. Limited vs. Advanced NextGen (3-way, p<.01) Advanced NextGen (speed error-nulling avionics) ( p g ) allows reduced TOA error for all speeds and number of traffic flow points 2. Limited NextGen (Quadratic x Linear, p<.01) Speed commands only (without speed error error- nulling avionics): p=.01 • Increase number of traffic flow points yields exponential reduction in TOA error • 14 kts best (turns typical taxi speed) (turns, • Replicated Williams, Hooey, & Foyle, 2006 Late 3. Advanced NextGen (Linear x Linear, p=.058) Early Speed error-nulling avionics: p g • Overall reduction in TOA error • 14 kts best (turns, typical taxi speed) • Linear improvement with more traffic flow points
  21. 21. TOA Error Distributions TOA error distribution results Advanced NextGen (error-nulling avionics) much less variable TOA error than Limited NextGen (speed commands)
  22. 22. Departure Clearance Verification Errors Departure clearance verification results Incorrect rejections: 3 / 400 nominal clearances, p(error)=.008 p(error) .008 - Likely due to heading text readout (N vs. NE) Incorrect acceptances: 2 / 32 off-nominal (mismatched), p(error)=.06 - Both 2nd mismatch, 1 in each NextGen implementation May be indicative of increased workload with time-based taxi clearances
  23. 23. Departure Clearance Verification Latency Limited NextGen vs. Advanced NextGen (interaction, p=.005) p=.005 Correct = “Accept” Correct = “Accept” Correct = “Reject”
  24. 24. Departure Clearance Verification Latency Limited NextGen – Speed commands * only, no error-nulling avionics: (overall, p<.05) *= Significant * Advanced NextGen – Error-nulling * avionics: (overall, p<.001) n.s. * Correct = “Accept” Correct = “Accept” Correct = “Reject”
  25. 25. Departure Clearance Verification Latency Compared to “current-day” baseline taxi, Advanced NextGen (error-nulling avionics) had longer latencies to: - Correctly accept correct clearances - Correctly reject incorrect clearances Compared to Limited NextGen (speed commands only), Advanced NextGen (error-nulling avionics) had longer latencies to: - Correctly reject incorrect clearances May be indicative of increased workload in Advanced NextGen Correct = “Accept” Correct = “Accept” Correct = “Reject” implementation
  26. 26. Post-study Questions How many ‘speed changes’ (Limited NextGen) or ‘traffic flow points’ (Advanced NextGen) per route are acceptable? All: “2-3” Were there too many ‘speed changes’ (Limited NextGen) or ‘traffic flow traffic points’ (Advanced NextGen)? (1, 3, or 5) Limited NextGen: 0% “yes” Advanced NextGen: 88% “yes” yes (p<.001)
  27. 27. Post-Study Structured Interviews 1.5 hr Post-study Structured Interview Findings Time-based Taxi Clearances • Improve airport efficiency • Pilot acceptance likely (efficiency gains) • Some concern for safety (“eyes in”) • Ground speed on PFD reasonable • Suggestions for TND to show nearby traffic and taxi holds • Possible increase in crew coordination – need for speed “callouts” callouts NextGen Tailored Departures (Datalinked flexible 4-D departures) • Improve system-level efficiency (routing) p y y( g) • Improve individual aircraft efficiency (fuel, time) • Decrease flight deck workload (direct upload of clearances into FMS) • General acceptance of concept - Terrain/traffic cleared by ATC y - No issue with unique routes (may help with complacency) - Cross-check of datalink and route loaded required; Reasonable as implemented • Some concern about how to “back up” unique complex routes - Pre-departure briefings ( p g (how do y describe to each other, manually fly?) you , y y ) - Emergency or off-nominal fall-back procedures (avionics failure, engine out) - Requires future research
  28. 28. Conclusions Commanded Speed • TOA compliance most accurate with moderate taxi - Arrive early for slower speeds; Late for faster speeds Segment Distance • TOA error largest with single (long) route segments NextGen Taxi Implementation • Requirement for Advanced NextGen error-nulling avionics q g - Limited NextGen speed commands TOA error too high/variable (could limit optimization by STMs) - Advanced NextGen error-nulling avionics substantially improves TOA compliance • However, Advanced NextGen error-nulling avionics: - May induce increased flight deck workload - Need to investigate procedures and aids to offset - Required conformance levels of speed and TOA ‘windows’ NextGen Tailored Departures • No major concept issues • Need for cross-check, verification • How to ‘back up’ unique complex routes (for briefing, emergency, off-nominal)
  29. 29. Piloted Simulation of NextGen Time-based Taxi Clearances and Tailored Departures David C. Foyle, PhD NASA Ames Research Center Becky L. Hooey, MSc C st a Christina L. Kunkle, BA u e, Martin F.J. Schwirzke, MA Deborah L. Bakowski, MA San Jose State University Foundation at NASA Ames Research Center ICNS 2009 http://humansystems.arc.nasa.gov/groups/HCSL/

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