CONCURRENT TASK DEMANDS IN THE COCKPIT: CHALLENGES AND VULNERABILITIES Loukia D. Loukopoulos R. Key Dismukes Immanuel B

1. CONCURRENT TASK DEMANDS IN THE COCKPIT: CHALLENGES AND VULNERABILITIES Loukia D. Loukopoulos R. Key Dismukes Immanuel Barshi NASA Ames Research Center Moffett Field, CA ALPA Training Council March 2003

2.  ? •  ? MOTIVATION • Complex operating environments • number • timing • and interaction of tasks •  automaticity •  habit •  flows, checklists •  procedures, phase of flight structure • Characterize nature of interaction • Characterize demand such interaction places on cognition • Qualitative approach • Jumpseat observation of routine flights • Boeing 737; 2 air carriers; 1-4 hours per leg; nation-wide • notes; informal interviews • Training (initial, transition/upgrade) • Written materials (manufacturer and carrier FOMs) • Incident reports (ASRS, NTSB, ASAP) • Work applies to all phases of flight: use Preflight and Taxi-out for illustration

3. assumed ideal • Errors pilot perspective (ASRS reports) real LAYERING • Ideal manufacturer perspective (manuals) • Assumed carrier perspective (FOMs, training) • Real observer perspective (jumpseating)

4. Manufacturer’s representation? (ideal)

5. PREFLIGHT - ideal (manufacturer) • Goals: • Pre-check systems operating properly • Configure aircraft for engine start and push-back (next phase of flight) • Configure for takeoff • Configure for flight • Considerations: • Safe operation of aircraft • Optimal performance of aircraft

6. Preflight B737 Ops Manual FLIGHT ALTITUDE indicator --- cruise altitude LANDING ALTITUDE indicator --- destination field elevation Pressurization mode selector --- AUTO AUTOMATIC FAIL light --- Extinguished PANEL OFF light --- Extinguished Set panel --- As desired WARNING: Do not key HF radio while airplane is being fueled. Injury to personnel or fire may result

7. Preflight - ideal (manufacturer) CAPTAIN FIRST OFFICER FLIGHT DECK PREPARATION procedure F L O W (17 items) Finish PREPARATION procedure FINAL PREPARATION procedure (2 items) Start checklist checklist complete Start checklist checklist complete FLIGHT DECK PREPARATION procedure F L O W (57 items) Finish PREPARATION procedure FINAL PREPARATION procedure (2 items) Ask for BEFORE START checklist (down to the line) Ask for BEFORE START checklist (below the line) BEFORE START checklist L I S T (24 items) CLEARED FOR START BEFORE START checklist L I S T (4 items) ENGINE START & PUSHBACK

8. A B C D E F G H         PHASE OF FLIGHT - ideal (manufacturer) CAPTAIN FIRST OFFICER • Linear, stable flow of events • Checklist is “meeting point” • Independent tasks • Independent operators • Reliance on habit (B always follows A) and triggers (F prompts G)

9. Carrier’s representation? (assumed)

10. PREFLIGHT - assumed (carrier) • Goals: • Pre-check systems operating properly • Configure aircraft for engine start and push-back (next phase of flight) • Configure for takeoff • Configure for flight • Considerations: • Safety • Performance of aircraft • Carrier (additional) considerations • Priorities (fuel, time, passenger comfort) • Type of operations (short/long-haul, turn-arounds, regions/airports, fleet) • Philosophy (safety, efficiency) • New technologies (ACARS, on-board performance computer) • Coordination with agents (dispatch, maintenance, company)

11. + x + y w A B C D E F G H if z then C'       • Complexity added but at pre-determined, predictable points in time • Some dependency of task but in non-explicit ways • Some interaction between operators • But still fundamentally linear flow of events  PILOT-driven operation PHASE OF FLIGHT - assumed (carrier) CAPTAIN FIRST OFFICER (be watching for w) *

12. Preflight - assumed (carrier) CAPTAIN FIRST OFFICER Cabin Attendant Gate Agent ACARs/OPC Review paperwork Sign flight release Prepare/review charts FLIGHT DECK PREPARATION procedure F L O W Finish PREPARATION procedure Review Load Schedule Review FMC Takeoff brief Ask for BEFORE START checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts FLIGHT DECK PREPARATION procedure F L O W Finish PREPARATION procedure (Passenger count) (Load Sheet) Program FMC Start BEFORE START checklist BEFORE START checklist complete MONITOR Ground frequency Company/Dispatch frequency MONITOR Interphone BEFORE START checklist L I S T ENGINE START & PUSHBACK

13. … and so it should all work as expected… … or maybe not?

14. TAXI-OUT -real Captain’s ASRS Report # 425357 (edited) “The aircraft we had for this flight had an inoperative fuel gauge, and an inoperative APU… DFW was in the midst of a departure rush. Since we had to do a crossbleed start, we did not do the After Start checklist immediately... We got clearance to taxi and requested a spot to do the start. We stopped ... as instructed and completed the start. As we were finishing, ground control was giving instructions to aircraft taxiing mentioning us in reference. We heard this, completed the after start checklist, and told ground we were ready to taxi. We were given instructions to hold short of taxiway WJ, give way to opposite direction traffic, then proceed N to taxiway Z to taxiway HY to taxiway Y across the bridge to taxiway J to taxiway EF for takeoff on runway 17R, follow an ACR aircraft. With all the above, taxiing to a new and unfamiliar runway (for this crew) in the dark, we didn't complete the before takeoff checklist. As we were cleared for takeoff and applied power, the takeoff warning horn sounded and we immediately realized that the flaps had not been extended for takeoff. There were many distractions leading up to this incident which should have been warning signals. • There was a time pressure element, we were running late and knew we had an airplane change in a short ground time in Denver before our next flight. • The APU and the necessity for the crossbleed start precluded the normal flow of calling for flaps and the before takeoff checklist as we taxi from the gate. • I was distracted by calling for taxi, so ground control knew we were ready to move. • Immediately after that call we were given a complicated taxi route with hold short and follow instructions and we were concentrating on finding the taxiways in the dark…”

15. Line representation (real)

16. Skipped over checklist item - interruption - departed without lobgook CAPTAIN FIRST OFFICER 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 inop - 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 PREFLIGHT errors attributed to “distractions” (incident reports) Review paperwork Sign flight release Prepare/review charts FLIGHT DECK PREPARATION procedure Finish PREPARATION procedure Review Load Schedule Review FMC Takeoff brief Ask for BEFORE START checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts FLIGHT DECK PREPARATION procedure Finish PREPARATION procedure (Passenger count) (Load Sheet) Program FMC Start BEFORE START checklist BEFORE START checklist complete ENGINE START & PUSH-BACK

17. Omitted call for flaps -rushed to clear ramp/gate area for arriving aircraft -aborted takeoff CAPTAIN FIRST OFFICER 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 FO failed to monitor CA – busy with flow; night taxi – taxi in wrong direction Flaps incorrectly set, missed noticing during checklist - crew busy with fuel problem, runway changes, programming FMC - aborted takeoff Confuse own position on taxiway diagram - new terminal; studying NOTAMs; runway change – taxied into ditch Omitted checking reason for bleed air indicator light-busy with delayed engine start and checklists - takeoff without troubleshooting FO failed to monitor CA -runway change; busy reprogramming FMC -taxied past intended taxiway Fail to confirm flap position - evaluating heavy rain showers; rushed to accept takeoff clearance - aborted takeoff 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 Omitted flaps - checklist interrupted by Tower; crew rushed to accept takeoff clearance - aborted takeoff Omit above-line Checklist - running late, checklist interrupted by Tower, unexpected clearance for takeoff - abort takeoff TAXI-OUT errors attributed to “distractions” (ASRS incidents) Ask for flaps Ask for taxi clearance Monitor radios Receive taxi clearance Form mental picture of taxi route Check for obstacles Start taxiing Perform PRE-TAKEOFF flow (above line) Ask for PRE-TAKEOFF checklist Monitor radios Monitor traffic Maintain positional and situational awareness Monitor Tower Receive clearance Perform PRE-TAKEOFF flow (below line) Ask for PRE-TAKEOFF checklist Line up with runway Set flaps Request taxi clearance Monitor radios Receive taxi clearance Acknowledge taxi clearance Form mental picture of taxi route Check for obstacles Perform PRE-TAKEOFF flow (above line) Start PRE-TAKEOFF checklist Monitor radios Monitor traffic Monitor position on airport chart Checklist complete Monitor aircraft movement Switch to Tower and monitor Receive clearance Acknowledge takeoff clearance Perform PRE-TAKEOFF flow (below line) Start checklist Checklist complete TAKEOFF

18. Wide range of outcomes • Large number of omissions not caught by later checklist • Consequences spill into all phases WHY? • $$$ ramp mishaps • $$$ taxiway/runway incursions • $$$ rejected takeoffs • $$$ time, fuel

19. Y w X *Wait for w *monitor for Z3 Z1 Z2 Z3 Z4 Z5 E F G H A B C D F'       • Complexity • Inter-dependency of tasks • Interaction between operators and • between operators and agents • Dynamic flow of events • Impossible to predict interactions • Impossible to pre-determine their timing ENVIRONMENT-driven operation PHASE OF FLIGHT - real CAPTAIN FIRST OFFICER

20. Preflight - real (compiled observations) Ramp and/or Ground? Check charts CAPTAIN FIRST OFFICER busy frequency Keep trying no time, familiarity Double-check charts no time, familiarity Conduct exterior walk-around Interruption Interruption Resume flow Inoperative item Inoperative item Call maintenance Still refueling Check fuel quantity and pumps Confirm Mx responded Confirm resolution Confirm Mx departed Confirm logbook on board PDC unavailable Defer programming FMC Passenger count unavailable Flight release still not picked up Request passenger count Look for ops/gate agent Delay at gate New PDC Re-program FMC APU off for 2 min before off-loading New flight release/PDC? Re-set MCP FO busy Re-flow trim & other settings Takeoff brief Time pressure Load sheet unavailable Defer programming FMC FO busy Flight plan/ Departure runway change Ask for Checklist Communicate with company Interruption Compute new performance #s Resume checklist Re-program FMS Re-brief Review paperwork Sign flight release Prepare/review charts FLIGHT DECK PREPARATION procedure Finish PREPARATION procedure Review Load Schedule Review FMC Takeoff brief Ask for BEFORE START checklist Obtain ATIS Obtain clearance Review paperwork Prepare/review charts FLIGHT DECK PREPARATION procedure Finish PREPARATION procedure (Passenger count) (Load Sheet) Program FMC Start BEFORE START checklist BEFORE START checklist complete MONITOR Ground frequency Company/Dispatch frequency MONITOR Flight Interphone BEFORE START checklist L I S T ENGINE START & PUSH-BACK

21. Taxi-out - real (compiled observations) Ramp and/or Ground? Environmental conditions Check charts CAPTAIN FIRST OFFICER Flaps before takeoff busy frequency busy frequency Keep trying Double-check charts no time, familiarity no time, familiarity De-icing pad Delayed engine start De-icing Checklist Before/After Start Checklist FMC: Program, set, verify Resume checklist short taxi, no time Extended taxi delay Just-in or new load data short taxi, no time Restart engine Keep head up/ outside Repeat checklists traffic, FO busy) Calculate & reset Performance data Defer checklist New/ Additional taxi instructions Inform Company (new #s, delays) Remember to follow aircraft Identify aircraft to follow Cross check with CA Remember taxi instructions Id taxiways and turns Stow OPC Remember to hold short Id correct place to hold short Interruption Resume checklist APU? Takeoff Brief: no time, familiarity Change in takeoff runway Change in takeoff sequence Consult charts Repeat Checklist? Accept/Plan/Request new runway no time Brief new runway no time Landing lights Strobes Shoulder harness Shoulder harness Radar? FMC update Ask for flaps Ask for taxi clearance Monitor radios Receive taxi clearance Form mental picture of taxi route Check for obstacles Start taxiing Perform PRE-TAKEOFF flow (above line) Ask for PRE-TAKEOFF checklist Monitor radios Monitor traffic Maintain positional and situational awareness Monitor Tower Receive clearance Perform PRE-TAKEOFF flow (below line) Ask for PRE-TAKEOFF checklist Line up with runway Set flaps Request taxi clearance Monitor radios Receive taxi clearance Acknowledge taxi clearance Form mental picture of taxi route Check for obstacles Perform PRE-TAKEOFF flow (above line) Start PRE-TAKEOFF checklist Monitor radios Monitor traffic Monitor position on airport chart Checklist complete Monitor aircraft movement Switch to Tower and monitor Receive clearance Acknowledge takeoff clearance Perform PRE-TAKEOFF flow (below line) Start checklist Checklist complete PRE-TAKEOFF checklist (above line) L I S T PRE-TAKEOFF checklist (below line) L I S T TAKEOFF

22. Challenge 1 • Pilots are constantly being interrupted • Interruptions demand attention and action • Such demands are unpredictable both in timing and in nature (e.g., Ground controller announces change in planned departure while crew involved in preflight procedures at the gate) Observed event : the FO received a call from Ground control notifying the crew of a change to their flight plan regarding the initial climb altitude in their departure. At that time, she was involved in setting the Pressurization panel as part of the Preparation flow … She suspended that activity and reached over to dial in the new altitude in the Mode Control Panel (MCP) altitude window while glancing over at the CA. She knew she had to verbally inform him of the change and to point out that she had already updated the MCP. She noticed that the CA was busy coordinating a luggage loading issue with the baggage handlers and Company, so she maintained the information in memory and formed an intention to carry out those actions at a later time. The FO resumed her flow, but monitored the CA’s activity. As soon as the luggage issue was resolved and the CA became available and able to redirect his attention to her again, she proceeded to inform him of the initial climb altitude change and the update to the MCP.

23. Challenge 2 • Pilots must often perform >1 tasks concurrently (e.g., captain doing preflight flow, looking for chart, first officer asks for load sheet, flight attendant reports item in galley needing service) Observed event : A request from the FO asking for the Load sheet that the CA had just finished reviewing a moment ago interrupted the CA in the process of looking through his binder for the relevant departure chart in the binder. The chart was obviously misplaced because the CA had trouble locating it. The CA closed the binder but used his finger as a bookmark pointing to the pages he had just looked through. While sifting through some papers on his left in search of the Load sheet, a Flight Attendant entered the cockpit to let the CA know he had identified a problem in the galley, had placed a call to the service crew, and would be informing him upon their departure and resolution of the problem. The CA momentarily directed his attention to the FA standing at the door behind him and acknowledged the situation. Upon redirecting his attention inside the cockpit and to his own activities he became re-engaged with the issue of the misplaced departure chart and went back to his binder. The FO’s second request for the Load Sheet reminded him he had neglected to locate it and he re-interrupted the search for the chart to find and hand the chart to the FO.

24. Challenge 3 • Pilots do not/cannot always initiate actions • circumstances may not be right for an action (e.g., must not extend flaps if taxiing in snow/icy conditions) • information/tool/agent may not be available for coordination (e.g., cannot proceed with checking final fuel load until refueling complete) Observed event: the CA reached the point on his preflight flow calling for verification of sufficient fuel on board. The fact that he still did not have a refueling slip on board made him realize that refueling was still underway. Rather than wait, and hoping for an on-time departure, he proceeded with the next step in the preflight flow. He formed the intention to conduct the fuel quantity check later (he may have also relied on the ensuing checklist which would, by definition, ask for number of gallons of fuel on board). When the Gate Agent brought the fuel slip for him to sign a few minutes later, he remembered the deferred intention and checked the fuel quantity readings.

25. WHY? • Challenges are underestimated • Vulnerabilities to making errors when facing such challenges are not appreciated

26. Vulnerabilities 1 Deferring activities (interrupted or new) • Must resume/start later requires • Deliberate formation of an intention • Remembering the existence of an intention • Remembering the exact content of intention (what was suspended & at which point/what needs to be done) • Remembering at a time when it is appropriate to carry out intention • (prospective) memory for intentions is poor 99% of memory errors in the cockpit involve PM (Nowinski, Holbrook, & Dismukes, 2003) • “triggers” for sequence of activities are disrupted and lost • intentions fade from working memory/focus of attention with time • other events continue to flow in habitual sequence and timing

27. Vulnerabilities 2 Interleaving activities (habitual/novel) • Combine two activities in previously/never-before encountered ways • Attend to two or more activities intermittently requires • Remembering each activity • Deciding when to check on progress of each activity • Remembering to check on progress of each activity • Monitoring • Essentially, a continuous prospective memory demand • Monitoring schedule for own /others’ progress? • “triggers” for sequence of activities are absent

28. Countermeasures • Acknowledge human fallibility • Vulnerable to interruptions • Examine procedures and checklists • Content • Timing • Identify source and nature of interruptions in each phase of flight • Apportion workload • Provide warning signs for pilots to look for • Establish triggers for items at risk (tie critical functions to fixed reference points) • Set traps (strict decision criteria not to cross unless all expected activities fulfilled) • Monitoring is a critical task • Better guidance needed (Sumwalt, Thomas, Dismukes, 2002)

29. ALPA Training Council March 2003

30. PREFLIGHT - real (Captain’s ASRS Report # 335059) “At this point the scheduled flight is about 1.5 hours behind schedule. Prior to our arrival… we experienced some problems with the autopilot system… my FO… contacted company operations, advised them of our time of arrival and called for fuel with an order for 1900 lbs… …once on the ground…I went inside the terminal to call Maintenance… got the information I needed and headed back to the aircraft to complete the paperwork. The passengers were boarding the flight and the FO was at the back of the aircraft… as we both got into the cockpit the FO started the load manifest. I then completed the write-up in the Maintenance Log and during this time asked the FO if the Before Start checks were complete. He answered 'no.' I then started the Before Start checks myself but was distracted by the events of a final baggage and passenger count for the Loadmanifest. …There (were)other flights on the ground and I had seen the fuel truck moving about… with the passengers and bags onboard and (the) doors closed, the engines were started and a call for taxi made... ...Construction has been going on at this airport on the main runway and we have been using a shorter runway… we were given taxi for runway 29. After a look at the takeoff data, winds and weights, we advised(Tower)we needed runway 22. The Tower then cleared us for takeoff on runway 22 but we had not completed the checklist and so we advised Tower and took the time to complete the checklist. Once completed we departed runway 22 … after climbing through 12000 ft MSL … I was scanning the instruments and noticed the fuel quantity only showed 980 lbs… I feel there were many distractions that interrupted the flows on the checklist and items were skipped..“