OPPORTUNITIES FOR AND VULNERABILITIES TO ERROR 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 Teams
  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?

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OUTLINE

• Errors in everyday flight operations pre-9/11
• Opportunities for error in work environment
  (operational factors)
• A qualitative analysis of line operations
• field observations (N50)
• 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

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This would never happen to us
error in everyday flight operations

• 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)

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OPPORTUNITIES FOR ERROR operational 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
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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

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textbook version
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
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real life demands
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? Loa
d/WB 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
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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? Loa
d/WB 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
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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

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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

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OPPORTUNITIES FOR ERROR operational factors
Taxi Out
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real life demands
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)
M O N I T O R
T A X I
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 Takeo
ff Briefing
Xx xx xx Recall Xx x xxx Transponder xx X xx
xxxx xxxxxxx
TAKEOFF
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errors observed (ASRS reports)
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 Takeo
ff 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
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TAXI OUT CA flow FO flow CA, FO
Checklist Checklist item
Aft Overhead
Aft Overhead


Forward Overhead
Forward Overhead


Mode Control Panel
FIRST OFFICER Instrument
CAPTAIN Instrument
Center Instrument
SEATBELT AND SHOULDER HARNESS
FLAPS
Forward Electronic
Control Stand
Aft Electronic
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VULNERABILITIES TO ERRORS cognitive factors
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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 arent any - its 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

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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

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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

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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.

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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
  its 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.

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COMPLACENCY

• Blanket excuse for errors Ill 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

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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 FAs
  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.

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Errors happen even to the most expert pilots -
WHY?

• Opportunities for error in work environment ?
• Vulnerabilities inherent in human cognitive
  abilities ?
• Illustration using an NTSB incident report

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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
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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_at_mail.arc.nasa.gov
ATA/CRM Conference MARCH 2002