Error Opportunities in Everyday Flight Operations

1. OPPORTUNITIES FOR AND VULNERABILITIES TO ERROR IN EVERYDAY FLIGHT OPERATIONS • Loukia D. Loukopoulos • Key Dismukes & Immanuel Barshi • NASA Ames Research Center, Moffett Field, CA ATA/CRM Conference MARCH 2002

2. BACKGROUND • Opportunities for and vulnerabilities to ERROR in everyday flight operations • research-oriented, theoretical approach • errors happen even to the most expert pilots - why? • Presented earlier this year at FAA annual review meeting • Discussed in the context of Rapid Response Team’s recommendations regarding security measures • Implications? • workload and distractions • how will measures, both outside and inside, the cockpit affect pilots’ performance? • how to avoid unintended opportunities for error?

3. OUTLINE • Errors in everyday flight operations pre-9/11 • Opportunities for error in workenvironment (operational factors) • A qualitative analysis of line operations • field observations (N=50) • two U.S. carriers, B737 • contrast between training and operating environment • evidence from incident reports • Focus on preflight and taxi • Vulnerabilities inherent in human cognitive abilities (cognitive factors) • Memory and attention limitations

4. “… error in everyday flight operations” “This would never happen to us…” • PREFLIGHT: While doing Before Start Engine checklist the agent brought in a jumpseat rider and I allowed the checklist to be interrupted. Engine Start and Push Back were normal. During Taxi I noticed the seat belt switch was in the “off” position. (ASRS 400770) • PUSHBACK: CA became involved in discussion regarding taxi instructions with FO just after communication with tug attendant. Assuming that tug had departed and that previous communication was confirmation of that, CA applied power to taxi and struck the tug. (NTSB CHI95LA170) • TAXI: FO busy starting #2 engine, then doing the After Start flow and Taxi flow in time to run the Taxi checklist prior to reaching the runway. CA taxied past the Hold Short line. (ASRS 317660) • CLIMB: Climbing through 16000ft, FA called and inquired about seat belt, rough ride, thunderstorms etc. This got both pilots occupied and to forget to do the Climb checklist, thus missing the altimeter setting change to 29.92. (ASRS 394580) • CRUISE: Master caution light illuminated. Preoccupied with handling problem (duct overheat), handling radios, stowing charts. Did not notice strong wind had blown aircraft E of course. (ASRS 427840) • APPROACH: Inbound to destination airport, thunderstorms all around. Unable to comply with instructions to hold at standard hold fix, then alternate fixes due to weather. Cleared to third hold fix. Meanwhile checking fuel, weather at alternate, talking to company, making PA, and interrupted by FA. Crew neglected to finish Descent checklist which was started several times. (ASRS 402510) • LANDING: While on visual approach crew could not get the ILS to tune or display. PM was busy trying to resolve the problem. Once inside the OM, both pilots turned their attention to the landing. With no one ahead of them and the runway clear, they missed the frequency change to Tower and landed while still on Approach frequency. (ASRS 453870)

5. OPPORTUNITIES FOR ERRORoperational factors: Preflight Note: assume through flight, no change in aircraft or flight crew, 737-300/500 Note: this will not be a discussion of weather, fatigue, or personal/emotional factors

6. PREFLIGHT: textbook version (any airline) • SOPs typically describe • Preflight flow (memory) • separate for CA and FO • may include optional checks (e.g., standby power check) • Preflight checklist (card) • not intended as “read and do” list • verification of “killer items” in preceding flow • Manuals discuss (to varying degrees) • Documentation required • Dispatch Release (acquisition, duration, amendment) • Weather • Airport information • Alternates • Flight plan changes • Fuel considerations

7. textbook version Gate Crew Push Back Crew Cabin Crew Maintenance Crew Baggage Handlers Jumpseat Rider(s) Flight release Load data Passenger count Fuel slip Passengers Food Rest Personal MONITOR Ground frequency Company/Dispatch frequency Cabin & cockpit temp • CAPTAIN • Review paperwork • Sign flight release • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • xxxxxxx • Fuel quantity • Xxx xxxx x Xxx • Xxxxxxxxxxxxxx Xxx • Parking brake • (20-30 items) • Finish PREFLIGHT flow • Review Load Schedule • Takeoff brief • Ask for PREFLIGHT checklist • FIRST OFFICER • Obtain ATIS • Obtain clearance • Review paperwork • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • Xx xx xx x Xxx Xxx • Air conditioning & Pressurization • FMC • Radios • Xxx • (20-30 items) • Finish PREFLIGHT flow • (Passenger count) • (Load Sheet) • Program FMC • Start PREFLIGHT checklist • PREFLIGHT checklist complete MONITOR Flight Interphone • PREFLIGHT checklist • Oxygen • Circuit Breakers • IRS selectors • Hydraulic pumps • xxx xxx xxx • Takeoff warning horn • Parking Brake • (10-15 items) • PUSHBACK

8. real life demands Ramp and/or Ground? Check charts busy frequency Keep trying no time, familiarity Double-check charts no time, familiarity IRSs need 10 min for alignment 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 PDC unavailable Confirm Mx departed Defer programming FMC Confirm logbook on board Passenger count unavailable Still not picked up Request pax count Look for ops/gate agent APU off for 2 min before off-loading New PDC Delay at gate Re-program FMC New flight release/PDC? Re-set MCP Re-flow trim & other settings Takeoff brief Load sheet unavailable Defer programming FMC FO busy/behind Flight plan/ Departure runway change Ask for Checklist Communicate with company Interruption Compute new performance #s Resume checklist Re-program FMS Re-brief • CAPTAIN • Review paperwork • Sign flight release • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • xxxxxxx • Fuel quantity • Xxx xxxx x Xxx • Xxxxxxxxxxxxxx Xxx • Parking brake • (20-30 items) • Finish PREFLIGHT flow • Flight Release? • Fuel Slip? • Maintenance? • Load/W&B schedule? • Passenger count? • Review Load Schedule • Takeoff Brief • Ask for PREFLIGHT checklist • FIRST OFFICER • Obtain ATIS • Obtain clearance • Review paperwork • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • Xx xx xx x Xxx Xxx • Air conditioning & Pressurization • Xxxxxxxxxxxxxx Xx • FMC • Radios • Xxx • (20-30 items) • Finish PREFLIGHT flow • (Passenger count) • (Load Sheet) • Complete programming FMC • Start PREFLIGHT checklist • PREFLIGHT checklist complete (compiled observations) • PREFLIGHT checklist • Oxygen • Circuit Breakers • IRS selectors • Hydraulic pumps • xxx xxx xxx • Takeoff warning horn • Parking Brake • (10-15 items) • PUSHBACK

9. errors observed (ASRS incidents) • CAPTAIN • Review paperwork • Sign flight release • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • xxxxxxx • Fuel quantity • Xxx xxxx x Xxx • Xxxxxxxxxxxxxx Xxx • Parking brake • (20-30 items) • Finish PREFLIGHT flow • Flight Release? • Fuel Slip? • Maintenance? • Load/W&B schedule? • Passenger count? • Review Load Schedule • Takeoff Brief • Ask for PREFLIGHT checklist • FIRST OFFICER • Obtain ATIS • Obtain clearance • Review paperwork • Prepare/review charts • Start PREFLIGHT flow • Xxxxx • Crew oxygen • Xx xx xx x Xxx Xxx • Air conditioning & Pressurization • Hydraulics • FMC • Radios • (20-30 items) • Finish PREFLIGHT flow • (Passenger count) • (Load Sheet) • Complete programming FMC • Start PREFLIGHT checklist • PREFLIGHT checklist complete Interruptions, workload, Defer notifying Mx of item noticed during walk-around: forgot to place call Omitted careful review of charts, missed speed restriction on SID- speed violation missed aircraft not refueled/ insufficient fuel: return to gate prior to taking off Missed aircraft not refueled/ insufficient fuel: discover in flight, return to airport Fuel pumps deferred because still refueling, then missed on checklist: engine starvation in flight Distractions, improper setting of pressurization:- cabin altitude warning light in cruise skipped Hydraulics item - rudder found “stiff” on flight controls check: return to gate, call mx Forgot to request updated PDC: take off without one Assumed other pilot had new PDC: depart without one Interruptions during preflight: failed to program new departure Acars inop, defer getting load sheet: takeoff without Jumpseat rider interrupts checklist: forget to turn seat belt sign on Omitted thorough check of CBs (flap): configuration warning horn at takeoff Omitted check of circuit breakers: landing gear horn at destination, go around • PREFLIGHT checklist • Oxygen • Circuit Breakers • IRS selectors • Hydraulic pumps • xxx xxx xxx • Takeoff warning horn • Parking Brake • (10-15 items) Interruptions, CA fails to notice FO programmed wrong flight plan Omitted check of CBs: unable to start engine, return to gate, call Mx Defer looking for logbook when noticed it was missing: depart without it Distractions, omit throttles item: pushback with throttles open, damage to aircraft CA failed to notice FO had programmed wrong squawk: confusion on climb out • PUSHBACK

10. PREFLIGHT: characteristics 1 of 2 • Non-linear structure • no predictable sequence of input events e.g., passenger count may be delivered before/after FMS has been programmed • no prescribed sequence of output events e.g., conduct departure brief before/after checklist • Flexible structure • no one prioritization scheme is prescribed e.g., manage security concern vs. conduct flow • no one scheme is applicable in every situation • Non-dependency of actions • step 2 does not always imply (previous ) step 1 has been accomplished e.g., can calculate performance data before starting checklist if time permits • Concurrent activity • simultaneous involvement of many external “agents” (experts) e.g., gate/operations agents, Ground, Maintenance, pushback crew, cabin crew, company • lack of awareness about others’ responsibilities, stressors, pressures, language • technically impossible not to pressure/interrupt one-another

11. PREFLIGHT: characteristics 2 of 2 • Inherent expectation that all systems are still “good to go” • just landed a “good” aircraft • Rhythm of ‘pushing ahead’ (even in the absence of real time pressure) • reinforced by repetitive nature and philosophy of operations • “blurs” the details of actions among many preflights in a given workday • 63% of ‘Hurry Up’ errors originate at preflight (68% of which are joint errors) • Constant interruptions and distractions • defer/delay actions • interleave activities, often in new, never practiced ways • prioritize and juggle concurrent demands • Inadvertent deviations from SOPs or personal habits can occur and easily remain undetected by self and/or other pilot

12. OPPORTUNITIES FOR ERRORoperational factors: Taxi Out

13. real life demands Environmental conditions Ramp and/or Ground? Flaps before takeoff Check charts 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 Program, set, verify Resume checklist short taxi, no time Extended taxi delay Just-in or new load data short taxi, no time traffic, FO busy) Restart engine Ask for Checklist Keep head up/ outside Repeat checklists Calculate & reset Performance data New/ Additional taxi instructions Inform Company (new #s, delays) Remember to follow aircraft Identify aircraft to follow Cross check with CA Stow OPC Remember taxi instructions Id taxiways and turns Resume checklist Interruption Remember to hold short Id correct place to hold short APU? no time, familiarity Landing lights Change in takeoff runway Change in takeoff sequence Radar? Consult charts Repeat Checklist? Accept/Plan/Request new runway no time Strobes Brief New runway no time FMC update Shoulder harness Shoulder harness • CAPTAIN • Ask for flaps • Ask for taxi clearance • Monitor radios • Receive taxi clearance • Form mental picture of taxi route • Check for obstacles • Start taxiing • Perform TAXI flow • Ask for TAXI checklist • Monitor radios • Monitor traffic • Maintain positional and situational awareness • Monitor Tower • Receive clearance • BEFORE TAKEOFF flow • Ask for checklist • Line up with runway • FIRST OFFICER • Set flaps • Request taxi clearance • Monitor radios • Receive taxi clearance • Acknowledge taxi clearance • Form mental picture of taxi route • Check for obstacles • Perform TAXI flow • Start TAXI checklist • Monitor radios • Monitor traffic • Monitor position on airport chart • TAXI checklist complete • Monitor CA and aircraft movement • Switch to Tower and monitor • Receive clearance • Acknowledge takeoff clearance • BEFORE TAKEOFF flow • Start checklist • Checklist complete (compiled observations) T A X I M O N I T O R • Xxx • Xxx xx xxxxxx • "0" Fuel Weight • FMC • xx • Xx xx xxx xxxx • Xxxx xx • xxx • Xx xxxxxxxxxxx • Flaps • Xxx xx x x • xx • Xxx xxx x • X xx xxxx • Xxx • xxxxxxx • x • Takeoff Briefing • Xx xx xx • Recall • Xx x xxx • Transponder • xx • X xx xxxx xxxxxxx • TAKEOFF

14. errors observed(ASRS reports) “Rushed” by aircraft pulling into same gate - omitted flaps - aborted takeoff Forgot to request new flight release after 1 hr ground stop Congested frequency - delay - start taxi mistakenly assuming clearance rec’d Assumed only need to contact ramp - taxied onto active runway behind gate Omitted checklist and has not restarted engine #1 - delay Misunderstand tower instructions - taxi onto runway w/o clearance • CAPTAIN • Ask for flaps • Ask for taxi clearance • Monitor radios • Receive taxi clearance • Form mental picture of taxi route • Check for obstacles • Start taxiing • Perform TAXI flow • Ask for TAXI checklist • Monitor radios • Monitor traffic • Maintain positional and situational awareness • Monitor Tower • Receive clearance • BEFORE TAKEOFF flow • Ask for checklist • Line up with runway • FIRST OFFICER • Set flaps • Request taxi clearance • Monitor radios • Receive taxi clearance • Acknowledge taxi clearance • Form mental picture of taxi route • Check for obstacles • Perform TAXI flow • Start TAXI checklist • Monitor radios • Monitor traffic • Monitor position on airport chart • TAXI checklist complete • Monitor CA and aircraft movement • Switch to Tower and monitor • Receive clearance • Acknowledge takeoff clearance • BEFORE TAKEOFF flow • Start checklist • Checklist complete CA briefed and FO set wrong flaps for aircraft type - warning horn at takeoff Omit - overrun runway hold line Forget to confirm tug clear - taxi into tug Mistook clearance to other aircraft for own - taxi without clearance • Xxx • Xxx xx xxxxxx • "0" Fuel Weight • FMC • xx • Xx xx xxx xxxx • Xxxx xx • xxx • Xx xxxxxxxxxxx • Flaps • Xxx xx x x • xx • Xxx xxx x • X xx xxxx • Xxx • xxxxxxx • x • Takeoff Briefing Fail to stop when lost - other aircraft had clearance canceled Busy running checklist - force other aircraft to go around Preoccupied with new departure clearance and packs-off operation and omit - aborted takeoff Confuse position - taxi into ditch Busy starting engine & running delayed engine xlist and taxi xlist - runway incursion Omit or incorrectly set- warning horn at takeoff Forget to turn ignition switch on - overtemp engine Inadvertently hit flip-flop switch - delay New FO on IOE expected to hear “position and hold” - runway incursion • Xx xx xx • Recall • Xx x xxx • Transponder • xx • X xx xxxx xxxxxxx Squawk incorrectly set during preflight - rush and fail to notice error before takeoff APU bleed source - lost both packs in flight - enter pre-stall buffet while troubleshooting • TAKEOFF

15. TAKEOFF BRIEFING TAKEOFF BRIEFING SEATBELT AND SHOULDER HARNESS TAXI OUT CA flow FO flow CA,FOChecklist Checklist item Aft Overhead Aft Overhead * * Forward Overhead Forward Overhead * * Mode Control Panel FIRST OFFICER Instrument Center Instrument CAPTAIN Instrument SEATBELT AND SHOULDER HARNESS FLAPS Forward Electronic Control Stand Aft Electronic

16. VULNERABILITIES TO ERRORScognitive factors

17. INTERRUPTIONS & DISTRACTIONS • Interruption: event that causes (momentary) suspension of ongoing activity • Distraction: event noticed and noted but remains ‘in background’ - pilot does not suspend task but mental processing may be impaired • Can be either expected or unexpected • nature and timing always unpredictable • Often underestimated because they are an integral part of everyday operations • “there aren’t any” - “it’s all one big interruption” • lack of research and training on the topic • Contributing factors in 50% of air carrier major accidents of past decade • Distractions: caused by non-related crew dialogue led FAA to impose ‘Sterile Cockpit Rule’ in 1981

18. AUTOMATICITY • Highly practiced procedures become automatic (vs. controlled) • absence of conscious mental effort • desirable outcome of training • Advantages • allows fast, smooth execution of a task • frees up attention resources • Disadvantages • no conscious control of accuracy and timing • led (misled) by environmental cues • Automated procedures are vulnerable to omission when they are • interrupted • performed outside normal sequence or context

19. DEFERRED TASKS 1 of 2 • Forced deferment • interruptions (flight attendant interrupts departure brief) • environmental/operational factors (defer flaps at taxi in icing conditions) • Elected deferment • time pressure (defer consulting charts because pilot has fair idea of taxi route) • workload reduction (defer programming FMC until final load numbers) • Deferred task = intention to remember to do something in the future (prospective memory) • Cannot maintain delayed intentions in focal attention • must retrieve from memory when opportunity for execution arises • retrieval requires noticing some cue associated with intention • availability of cues and noticing cues is haphazard • Thus, memory lapses are commonplace

20. DEFERRED TASKS 2 of 2 • Remembering deferred intentions • e.g., call from Ground interrupts FO conducting preflight checklist • physical cue available and practical (finger, card) • e.g., new load numbers during taxi, must inform company after takeoff • physical cue not available or practical, but create artificial ‘trigger’ by tying deferred task to habitual future action (calling time off/out upon climb out) • e.g., delivery of passenger count interrupts CA conducting a takeoff brief • interruption not noted, no ‘red flag’ and no cue is practical • Chances of remembering increase with use of cues as reminders • (ASRS 398323)During walkaround I discovered a discrepancy (open access panel) that required a call to maintenance. I finished the walkaround and intended to call maintenance… upon reentering the aircraft I allowed myself to become distracted with other problems and forgot to place the call. Aircraft would not pressurize after takeoff.

21. SIDETRACKING • Attention drawn partly away from ongoing task • e.g., in response to an interruption (to assess its importance, priority, and implications) • (ASRS 425830) I discovered the logbook was missing (during Preflight flow)... I allowed myself to get sidetracked during my search for it by FA concerns in the back. FO also realized it’s absence during preflight but decided to call it later... a jumpseat rider entered and interrupted the checklist at the point where absent logbook would have been noticed. Aircraft departed the airport without the aircraft logbook. PREOCCUPATION • Attention drawn exclusively away from one task at the expense of another • e.g., in response to • a change in conditions affecting future task(weather, traffic) • anxiety (emergency, new procedure) • (ASRS 455570) CA working with maintenance on APU problem. With ten minutes to go, FO discovers departure runway has changed, is reprogramming new departure and intends to review unfamiliar departure. CA pushing to start engine #1 before APU quits and to run checklists. Crew pushes back, APU fails again, so crew now has to coordinate a crossbleed start and get approval for dispatch without APU… both pilots failed to review restrictions on SID and company page, and exceed speed restriction on climb out.

22. “COMPLACENCY” • Blanket excuse for errors: “I’ll be more careful next time,” “Fatigue” • Just a label? • Real reasons • Appearance of normalcy • repetitive nature of flight operations • high probability of success • Habit capture • virtually impossible to resist automatically performing a well-practiced, habitual task • natural to be unable to put thought and effort into performing tasks that have become automatic • Tempo of flows and checklists • inadvertently “fly through” checklists and procedures • Assumptions • Assume other pilot has copied taxi instructions correctly • Assume entire radio set up correctly when dialing in new frequency • Assume no obstacles because Ground is sequencing all aircraft on taxiways (look but not see) • Expectations • runway used in previous x number of takeoffs or on PDC • approach typically used at this airport at this time of year • type of aircraft usually flown • (ASRS 453640) FO set FMC at gate, I verified route and performance data, noted the cruise altitude he had set and checked the pressurization system. I did not crosscheck the cruise altitude with the PDC as is my usual practice. He had set everything up for FL310 while paperwork indicated FL350… I had relaxed my vigilance because the FO and I flew same aircraft in military and knew some of the same people. Contributing factors may be lower alertness due to early wake-up.

23. TRIGGERS • Many actions rely on natural ‘triggers’ • environmental cues (reset altimeter at specific altitude) • preceding actions (brief approach after receiving ATIS) • others’ actions (start checklist when PF asks for it) • Certain events disrupt presence of ‘triggers’, or remove them entirely • environmental factors (pushing back on one engine) • addition/deletion of task (security brief) • abnormal indication/situation (respond to FA’s concerns about a cabin situation) • pressure (receive pushback clearance and proceed to start without ensuring cabin ready) • … In the meantime, events continue to occur in their normal sequence • Difficult to notice absence or disruption of triggers • Pilots devise their own ‘triggering’ strategies • finish After Start checklist, put hand on Flap lever • (ASRS 379824) At completion of pushback I set the parking brake, completed engine start and verbally released the pushback crew - they acknowledged. We completed the After Start checklist, received taxi clearance, and began to taxi. Just as we moved the aircraft, they ran into my visual area and signaled an emergency stop. I then realized that I had not received nor responded to an “all clear” signal. The problem occurred because an inordinately long time elapsed after verbally releasing the ground crew and when we normally receive a “clear” signal… during that time frame, which was 3 times longer than normal, I completed all checklists, got clearance, and forgot that I had not been given the “thumbs up’ signal.

24. Errors happen even to the most expert pilots - WHY? • Opportunities for error in workenvironment  • Vulnerabilities inherent in human cognitive abilities • Illustration using an NTSB incident report

25. Distraction Defer starting preflight flow • Throttle check • Throttle check Interruption Interruption Leads to step normally later in checklist Sidetrack: brings maintenance issue back to foreground Omits check(?) and response Distraction Leads to step normally later • Throttle check Distraction Expectation, assumption PREFLIGHT case study NYC01LA077 Distraction Good technique: resume checklist prior to interruption Interruption Distraction Interruptions Automaticity: accept double challenge; 1 response to 2 challenges Interruption Rushing through checklist: 2 challenges together • (“fuel panel” never responded to,7 other challenges never mentioned) Preoccupation Preoccupation Automaticity, habit capture • Throttles not fully closed

26. OPPORTUNITIES FOR AND VULNERABILITIES TO ERROR IN EVERYDAY FLIGHT OPERATIONS Loukia D. Loukopoulos Human Factors Division, MS 262-4 NASA Ames Research Center Moffett Field, CA 94035 650-604-2843 llouko@mail.arc.nasa.gov ATA/CRM Conference MARCH 2002