Enhancing Airport Safety: Understanding Concurrent Task Demands and Pilot Error

1. Concurrent Task Demands and Pilot Error in Airport Surface Operations Key Dismukes, Loukia Loukopoulos, Immanuel Barshi Human Factors Research and Technology Division NASA-Ames Research Center and U.S. Navy Aerospace Experimental Psychology November 2003 FSF IASS, Washington D.C.

2. Consequences of Inadvertent Procedural Omissions • LaGuardia (1994): MD-82 ran off runway end after high-speed rejected take-off • NTSB: Anomalous airspeed indications caused by failure to turn on pitot heat • Detroit (1987): DC-9 crashed shortly after take-off • NTSB: Crew failed to set flaps/slats to take-off position • Dallas (1988): B-727 crashed shortly after take-off • NTSB: Crew failed to set flaps/slats to take-off position ------------------------------------------------------------------------ • Houston (1996): DC-9 landed gear-up • NTSB: Hydraulic boost pump not set to high position

3. Other consequences of overlooked procedural steps • Runway incursions • Broken tow-bars • Taxi into ditch • Engine flame-out • Overtemp engine • Flew wrong departure route • Go-around • Departed with inadequate fuel • APU left running during takeoff -- fire • Packs failed in cruise • Took-off without PDC • Deviated from speed or altitude restriction • Nose gear failed to retract • etc. Were These Accidents Unique? Not according to recent ASRS reports: • Rejected take-offs • Anomalous airspeed indications (pitot heat not on) • Configuration warning (flaps or trim not set) Unnecessary costs and delays But for luck any of these incidents might have become accidents

4. Why? • Why would experienced crews forget a procedural step they normally perform day in and day out? • Why fail to catch omissions with checklists?

5. An Ongoing NASA Research Project • “Carelessness” not an adequate explanation • Crews vulnerable to omissions when: • Interrupted or preoccupied with one of several concurrent tasks (Young, Dismukes, & Sumwalt, 1998). • Deferring tasks out of normal sequence (Loukopoulos, Dismukes, & Barshi, 2003). • Vulnerability to error among experienced pilots largely driven by: • Characteristics of tasks performed • Demands tasks place on human cognitive processes • Operating environment • Norms for actual line operations

6. Jumpseat Observation Study(Loukopoulos, Dismukes, & Barshi, 2003) • Reviewed FOMs, observed line operations, analyzed ASRS, NTSB reports. • All phases of flight — focus today on preflight and taxi • Discovered disconnect between FOM/training and actual line operations in area of task management.

7. Preflight - In theory (FOM) Ground/ Company/ Dispatch Frequencies Interphone Cabin Attendant Gate Agent ACARs / OPC CAPTAIN FIRST OFFICER Review paperwork Sign flight release Prepare/review charts Review Load Schedule Review FMC Takeoff brief Ask for checklist • Ask for checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) Program FMC Begin checklist Checklist complete Begin checklist Checklist complete procedure procedure checklist CLEARANCE checklist ENGINE START & PUSHBACK

8. Depiction of Cockpit Task Management in FOM/Training • Linear: task A task B task C in a fixed sequence.

9. Preflight - In theory (FOM) Ground/ Company/ Dispatch Frequencies Interphone Cabin Attendant Gate Agent ACARs / OPC CAPTAIN FIRST OFFICER Review paperwork Sign flight release Prepare/review charts Review Load Schedule Review FMC Takeoff brief Ask for checklist • Ask for checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) Program FMC Begin checklist Checklist complete Begin checklist Checklist complete procedure procedure checklist CLEARANCE checklist ENGINE START & PUSHBACK

10. Depiction of Cockpit Task Management in FOM/Training • Linear: task A task B task C in a fixed sequence. • Controllable: tasks are initiated by crew at their discretion. • Predictable: • Information available to crew when needed. • Individuals can communicate as needed.

11. Preflight - In theory (FOM) Ground/ Company/ Dispatch Frequencies Interphone Cabin Attendant Gate Agent ACARs / OPC CAPTAIN FIRST OFFICER Review paperwork Sign flight release Prepare/review charts Review Load Schedule Review FMC Takeoff brief Ask for checklist • Ask for checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) Program FMC Begin checklist Checklist complete Begin checklist Checklist complete procedure procedure checklist CLEARANCE checklist ENGINE START & PUSHBACK

12. Taxi-out - In theory (FOM) CAPTAIN FIRST OFFICER Captain Start taxiing Ask for checklist Receive takeoff clearance Ask for checklist Line up with runway First Officer Receive taxi clearance Start checklist Checklist complete Receive takeoff clearance Start checklist Checklist complete MONITOR Ground Company/Dispatch MONITOR Ground Company TaxiClearance MONITOR Captain taxiing Takeoff Clearance TAKEOFF

13. Depiction of Cockpit Task Management in FOM/Training • Linear: task A task B task C in a fixed sequence. • Controllable: tasks are initiated by crew at their discretion. • Predictable: • Information available to crew when needed. • Individuals can communicate as needed. • Overall picture: flight operations are pilot- driven and under moment-to-moment control of crew.

14. Review paperwork Sign flight release Prepare/review charts Review Load Schedule Review FMC Takeoff brief Ask for checklist Ask for checklist Preflight - the reality Conduct exterior walk-around no time, familiarity Ramp and/or Ground? Check charts busy frequency Keep trying Double-check charts no time, familiarity Interruption Interruption Resume flow Still refueling Check fuel quantity and pumps Inoperative item Inoperative item Call maintenance Confirm Mx responded Passenger count unavailable Confirm resolution Request passenger count Confirm Mx departed Data unavailable Confirm logbook on board Defer programming FMC Flight release still not picked up Look for ops/gate agent New PDC Delay at gate Re-program FMC New flight release/PDC? Re-set MCP Time pressure FO busy Re-flow trim & other settings Ask for checklist Takeoff brief Flight plan/ Departure runway change Interruption Resume checklist Communicate with company Compute new performance #s Re-program FMS Re-brief CAPTAIN FIRST OFFICER Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) Program FMC Begin checklist Checklist complete Begin checklist Checklist complete Ground/ Company/ Dispatch Frequencies Interphone Cabin Attendant procedure Gate Agent ACARs / OPC procedure procedure checklist CLEARANCE checklist ENGINE START & PUSHBACK

15. Review paperwork Sign flight release Prepare/review charts Review Load Schedule Review FMC Takeoff brief Ask for checklist Ask for checklist Preflight - the reality Conduct exterior walk-around no time, familiarity Ramp and/or Ground? Check charts busy frequency Keep trying Double-check charts no time, familiarity Interruption Interruption Resume flow Still refueling Check fuel quantity and pumps Inoperative item Inoperative item Call maintenance Confirm Mx responded Passenger count unavailable Confirm resolution Request passenger count Confirm Mx departed Data unavailable Confirm logbook on board Defer programming FMC Flight release still not picked up Look for ops/gate agent New PDC Delay at gate Re-program FMC New flight release/PDC? Re-set MCP Time pressure FO busy Re-flow trim & other settings Ask for checklist Takeoff brief Flight plan/ Departure runway change Interruption Resume checklist Communicate with company Compute new performance #s Re-program FMS Re-brief CAPTAIN FIRST OFFICER Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) Program FMC Begin checklist Checklist complete Begin checklist Checklist complete Ground/ Company/ Dispatch Frequencies Interphone Cabin Attendant procedure Gate Agent ACARs / OPC procedure procedure checklist CLEARANCE checklist ENGINE START & PUSHBACK

16. Taxi-out - the reality CAPTAIN FIRST OFFICER Ice/Snow Defer takeoff flaps Ramp and/or Ground? Check charts Keep trying Unfamiliarity with airport Consult charts busy frequency Consult charts “Clear” ramp area Form mental picture of route Unfamiliarity with airport Acknowledge clearance Ice/Snow Busy airport/ departure rush Form mental picture of taxi route De-icing Checklist Confirm CA’s understanding MONITOR airport traffic MONITOR aircraft position on chart APU? Packs? Extended taxi delay Restart engine Delayed engine start Just-in or new load data traffic, FO busy Repeat checklists Before/After StartChecklist Defer checklist Calculate & reset Performance data New/ Additional taxi instructions FMC: program/verify Remember taxi instructions Id taxiways and turns Keep head up/ outside Interruption Inform Company (new #s, delays) Resume checklist Remember to follow aircraft Identify aircraft to follow Cross check with CA Remember to hold short Id correct place to hold short busy frequency MONITOR Tower frequency APU off for 2 min before off-loading Keep trying Change in takeoff runway Accept new runway? Acknowledge clearance Consult charts Confirm CA’s understanding Brief new runway Strobes FMC update Change in takeoff sequence Shoulder harnesses FO’s leg Landing lights Repeat Checklist Take control of aircraft while finishing checklist Radar? “Clear” runway Start taxiing Ask for checklist Receive takeoff clearance Ask for checklist Line up with runway Receive taxi clearance Start checklist Checklist complete Receive takeoff clearance Start checklist Checklist complete MONITOR Ground//Dispatch MONITOR Ground/Company Taxi Clearance MONITOR Captain taxiing Takeoff Clearance TAKEOFF

17. Line Observations Reveal a Different Story • Each pilot must juggle several tasks concurrently. • Crews are frequently interrupted. • External demands arrive at unpredictable moments. • Conditions sometimes force task elements to be performed out of normal sequence. • Normal line operations are quite dynamic:

18. Line Observations Reveal a Different Story • Normal line operations are quite dynamic: • Each pilot must juggle several tasks concurrently. • Crews are frequently interrupted. • External demands arrive at unpredictable moments. • Conditions sometimes force task elements to be performed out of normal sequence. • Crews must at times struggle to maintain control of the timing and sequence of their work tasks. • Little guidance or training.

19. Conflict Between Theory and Reality • FOM is a powerful tool for safety by providing: • Operational reality disrupts ideal execution of procedures • Explicit description of how each task is to be performed • Standardization across crews • Checklists and checking procedures

20. So What? • Pilots become accustomed to concurrent task demands, interruptions, distractions and disruptions. • However these situations substantially increase vulnerability to error, especially omission of critical procedural steps.

21. Skipped over checklist item - interruption - departed without lobgook Forgot to call maintenance - distractions - depart with hatch installed backwards Neglected to add MEL to flight release - multiple distractions, busy with preflight - discovered en route Forgot logbook at ramp - kept deferring to check it; distractions; busy with preflight - discovered en route Never finished review of maintenance log - interruptions - aircraft flown with “open” item in logbook Omitted review of (SID) charts - distractions - speed violation on departure Missed aircraft not refueled - checklist interrupted - return to airport after taking off Skipped over checklist item - fuel pumps deferred during preflight because refueling - engine starvation in flight Skipped over checklist item - interruptions - discover insufficient fuel after pushback Omitted flow and checklist items - interruptions; delay; change in departure runway - discover insufficient fuel at 12000 ft Missed checking main tank fuel quantity - distractions - departed with insufficient fuel Forgot to request updated PDC - distractions; misled because preflight already complete - take off with expired PDC Improper setting of pressurization during preflight flow - interruptions - cabin altitude warning light in cruise Entered wrong weight into FMS - tail strike at takeoff Failed to program new departure - interruptions during preflight - discover after takeoff Omit requesting Load sheet - defer during preflight; ACARS inoperative - takeoff without load sheet Forgot to complete preflight flow - interruption - took off with APU running Forgot to request PDC - deferred when instructed to request by voice, not ACARS - discover after takeoff Omitted check of circuit breakers - busy with preflight; rushing - unable to start engine after pushback Checklist item read but not verified - interruption - pushback with emergency door slides armed Skipped checklist item - interruption - push back with Seat Belt signs off Read but not verify checklist item - distractions - pushback with throttles open, damage to aircraft Sample of Preflight errors CAPTAIN FIRST OFFICER Review paperwork Sign flight release Prepare/review charts Review FMC Takeoff brief Ask for checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts (Passenger count) (Load Sheet) g Program FMC Begin checklist Checklist complete Begin checklist Checklist complete CLEARANCE ENGINE START & PUSHBACK

22. Start taxiing Ask for checklist Receive takeoff clearance Ask for checklist Line up with runway Omitted call for flaps -rushed to clear ramp/gate area for arriving aircraft -aborted takeoff Started taxi without clearance - trouble-shooting problem with engine start - nearly hit ground handler Started taxi without clearance – rushed by other aircraft waiting to pull into gate; radio congestion; marshaller’s headset inoperative – query by ground controller CA taxied without having fully understood instructions - busy looking at other aircraft on taxiway and ramp - ground controller issued warning Started taxi without clearance - crew discussing taxi instructions - struck pushback tug Incorrect trim setting - checklist interrupted after item had been read but not verified - aborted takeoff Failed to start engine #-2 - distracted while discussing special operations for destination; omitted checklists - delay takeoff Neglected to set flaps -preoccupied with new departure clearance and packs-off operation -aborted takeoff FO failed to monitor CA - busy checking and correcting calculations of load data - taxi past hold short line Omitted flaps - crew discussing problem with APU, delayed flaps due to snow - aborted takeoff Flaps incorrectly set, missed noticing during checklist - crew busy with fuel problem, runway changes, programming FMC - aborted takeoff FO failed to monitor CA – busy with flow; night taxi – taxi in wrong direction Omitted checking reason for bleed air indicator light-busy with delayed engine start and checklists - takeoff without troubleshooting Confuse own position on taxiway diagram - new terminal; studying NOTAMs; runway change – taxied into ditch Fail to confirm flap position - evaluating heavy rain showers; rushed to accept takeoff clearance - aborted takeoff FO failed to monitor CA -runway change; busy reprogramming FMC -taxied past intended taxiway FO failed to monitor CA - busy with pre-takeoff preparations - aircraft crossed hold short line Omitted flaps - checklist interrupted by thrust reverser light; crew busy troubleshooting - aborted takeoff Omitted checklist - busy with delayed engine start and checklists; rushed to accept takeoff clearance - flaps not set, aborted takeoff Misunderstood Tower instruction - new FO on IOE, CA coaching FO - taxi onto runway w/o clearance Flaps incorrectly set - late paperwork ; runway change; programming FMC; short taxi; rushed to accept takeoff clearance- aborted takeoff Omit above-line Checklist - running late, checklist interrupted by Tower, unexpected clearance for takeoff - abort takeoff Omitted flaps - checklist interrupted by Tower; crew rushed to accept takeoff clearance - aborted takeoff Sample of Taxi-out errors CAPTAIN FIRST OFFICER Receive taxi clearance Start checklist • TAKEOFF

23. Why So Vulnerable to These Errors?

24. 1) “Controlled” processing Corresponds to conscious attention Slow, serial, and effortful: low capacity Required for tasks with novel aspects 2) Automatic processing Fast, minimal effort, high capacity Develops with extensive practice of habitual procedure Requires minimal conscious supervision Why So Vulnerable to These Errors? • Brain has two ways of processing information to perform tasks: • Cockpit tasks vary from requiring mainly controlled processing to being largely automatic.

25. Automatic processing has enormous advantages but also has serious vulnerabilities

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27. Vulnerabilities of Automatic Processing • If procedural flow is interrupted, chain is broken. • Pause prevents one step from triggering the next. • Initiation of automatic process depends on receiving signal or noticing a cue in the cockpit environment. • If signal does not occur, individual is not prompted to initiate procedure.

28. Vulnerabilities of Automatic Processing • If procedural flow is interrupted, chain is broken. • Pause prevents one step from triggering the next. • Initiation of automatic process depends on receiving signal or noticing a cue in the cockpit environment. • If signal does not occur, individual is not prompted to initiate procedure. • Highly practiced procedures and checklists tend to develop “look without seeing” automatic responses. • High workload and/or rushing prevent conscious supervision of automatic processes — exacerbates vulnerability.

29. Vulnerability to Errors of Omission Can Be Reduced 1) Actions airline operations and training departments can take 2) Actions individual pilots can take

30. Ways airlines Can Reduce Vulnerabilities • Analyze actual line ops write procedures to minimize opportunities for disruptions. • Avoid “floating” procedural items allowed to be performed at varying times. • Anchor critical items (e.g., setting takeoff flaps) to distinct step that cannot be forgotten (e.g., before start of taxi).

31. Ways airlines Can Reduce Vulnerabilities • Analyze actual line ops write procedures to minimize opportunities for disruptions. • Avoid “floating” procedural items allowed to be performed at varying times. • Anchor critical items (e.g., setting takeoff flaps) to distinct step that cannot be forgotten (e.g., pushback). • Analyze actual fleet “norms” for how checklists are executed and bottom-lines observed. • LOSA

32. Ways airlines Can Reduce Vulnerabilities • Analyze actual line ops write procedures to minimize opportunities for disruptions. • Avoid “floating” procedural items allowed to be performed at varying times. • Anchor critical items (e.g., setting takeoff flaps) to distinct step that cannot be forgotten (e.g., pushback). • Analyze actual fleet “norms” for how checklists are executed and bottom-lines observed. • LOSA • Train with realistic concurrent task demands

33. Ways Pilots Can Reduce Vulnerability • Being aware of vulnerability reduces threat. • Especially vulnerable when head-down, communicating, searching for traffic, or managing abnormals. • When interrupted or deferring a task: • Pause to encode intention to resume • Create conspicuous cue as reminder • Develop habit of deliberate execution of procedures and checklists to allow controlled supervision of habitual responses. • Avoid rushing.

34. Ways Pilots Can Reduce Vulnerability • Being aware of vulnerability reduces threat. • Especially vulnerable when head-down, communicating, searching for traffic, or managing abnormals. • When interrupted or deferring a task: • Pause to encode intention to resume • Create conspicuous cue as reminder • Develop habit of deliberate execution of procedures and checklists to allow controlled supervision of habitual responses. • Avoid rushing. • Pause at critical junctures to review. • Schedule / reschedule activities to minimize concurrent task demands (e.g., brief before TOD). • Treat monitoring as essential task (Sumwalt).

35. For further information: http://human-factors.arc.nasa.gov/ihs/flightcognition/ This work is supported by NASA’s Airspace Systems Program and by the FAA (AFS-230), Dr. Eleana Edens, program manager.