Key Dismukes, Loukia Loukopoulos, Immanuel Barshi Human Factors Research and Technology Division...

Key Dismukes, Loukia Loukopoulos, Immanuel BarshiHuman Factors Research and Technology Division

NASA-Ames Research Center

and

U.S. Navy Aerospace Experimental Psychology

November 2003

FSF IASS, Washington D.C.

Concurrent Task Demands and Pilot Error in

Airport Surface Operations

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

Were These Accidents Unique?

• Rejected take-offs– Anomalous airspeed indications (pitot heat not on)– Configuration warning (flaps or trim not set)

Not according to recent ASRS reports:

– 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.

• 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

Unnecessary costs and delaysBut for luck any of these incidents might have become accidents

Why?

• Why would experienced crews forget a procedural step they normally perform day in and day out?

• Why fail to catch omissions with checklists?

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

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.

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICERPreflight - In theory (FOM)

Obtain ATIS

Obtain clearance

Review paperwork

Prepare/review charts

(Passenger count)

(Load Sheet)

Program FMC

Begin checklist

Checklist complete

Begin checklistChecklist complete

ENGINE START & PUSHBACK

Review paperwork

Sign flight release


Review Load Schedule

Review FMC

Takeoff brief

Ask for checklist

•Ask for checklist

CLEARANCE

procedure

procedure

checklist

checklist

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone

Ground/Company/Dispatch

Frequencies

Depiction of Cockpit Task Management in FOM/Training

• Linear: task A task B task C in a fixed sequence.


Obtain ATIS

Obtain clearance

Review paperwork


(Passenger count)

(Load Sheet)

Program FMC

Begin checklist

Checklist complete



Review paperwork

Sign flight release



Review FMC

Takeoff brief

Ask for checklist


CLEARANCE

procedure

procedure

checklist

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone


Frequencies

checklist



• Controllable: tasks are initiated by crew at their discretion.

• Predictable:– Information available to crew when needed.– Individuals can communicate as needed.


Obtain ATIS

Obtain clearance

Review paperwork


(Passenger count)

(Load Sheet)

Program FMC

Begin checklist

Checklist complete



Review paperwork

Sign flight release



Review FMC

Takeoff brief

Ask for checklist


CLEARANCE

procedure

procedure

checklist

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone


Frequencies

checklist

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICERFirst Officer

Receive taxi clearance

Start checklist

Checklist complete

Receive takeoff clearance

Start checklist

Checklist complete

Captain

Start taxiing

Ask for checklist


Ask for checklist

Line up with runway

Taxi Clearance

MONITORGround

Company

Takeoff Clearance

MONITOR Ground

Company/Dispatch

MONITOR Captain taxiing

TAKEOFF

Taxi-out - In theory (FOM)



• 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.

Obtain ATIS

Obtain clearance

Review paperwork


(Passenger count)

(Load Sheet)

Program FMC

Begin checklist

Checklist complete



Review paperworkSign flight releasePrepare/review charts


Review FMC

Takeoff brief

Ask for checklist

Ask for checklist

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICER

CLEARANCE

procedure

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone


Frequencies

Preflight - the reality

Interruption

FO busy

Interruption

busy frequencyKeep trying

Ask for checklist

Resume flow

Inoperative item

Time pressure

Inoperative item

Flight release still not picked up

no time, familiarity

Interruption

Delay at gate

Ramp and/or Ground?

Flight plan/Departure runway change

Conduct exterior walk-around

no time, familiarity

New PDC

Still refueling

Data unavailable

Passenger count unavailable

Call maintenance

Look for ops/gate agent

Double-check charts

Resume checklist

Confirm Mx responded

Confirm Mx departed

Confirm resolution

Confirm logbook on board

Check charts

Defer programming FMC

Communicate with companyCompute new performance #s

Re-program FMS

Re-program FMC

Check fuel quantity and pumps

Re-brief

Re-flow trim & other settings

New flight release/PDC?Re-set MCP

Takeoff brief

Request passenger count

procedure

procedure

checklist

checklist

TAKEOFF


Start checklist

Checklist complete


Start checklist

Checklist complete

Start taxiing

Ask for checklist


Ask for checklist

Line up with runway

Taxi Clearance

MONITORGround/Company

Takeoff Clearance

MONITOR Captain taxiing

Taxi-out - the realityMONITOR

Ground//Dispatch

Acknowledge clearance

Form mental picture of taxi routeConfirm CA’s understanding

Remember taxi instructionsId taxiways and turns

Remember to follow aircraftIdentify aircraft to follow

Remember to hold shortId correct place to hold short

New/ Additional taxi instructions

Unfamiliarity with airport


Strobes

LandinglightsRadar?

“Clear” ramp areaConsult charts

Shoulder harnesses

FMC update

“Clear” runway

APU off for 2 min before off-loading

Keep head up/ outside

Calculate & reset Performance data

Inform Company (new #s, delays)

Cross check with CA

FMC: program/verify

Keep trying

MONITORaircraft position on chart

MONITORTower frequency

MONITOR airport traffic

Acknowledge clearanceConfirm CA’s understanding

Defer takeoff flaps

Defer checklist

Restart engineRepeat checklists

Brief new runway

Check charts

De-icing Checklist

APU? Packs?

Repeat Checklist Take control of aircraft while finishing checklist

Accept new runway?

Consult charts

Keep trying

Consult charts

Before/After StartChecklist

Form mental picture of route

Resume checklist

Just-in or new load data

busy frequency

Interruption

Ice/Snow

Ice/Snow

traffic, FO busy

Change in takeoff runway

Change in takeoff sequence FO’s leg

Ramp and/or Ground?

Extended taxi delay

Busy airport/ departure rush

Unfamiliarity with airport

Delayed engine start

busy frequency

– 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.

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.

Line Observations Reveal a Different Story

• Normal line operations are quite dynamic:

• Crews must at times struggle to maintain control of the timing and sequence of their work tasks.

– Little guidance or training.

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

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.

•

Obtain ATIS

Obtain clearance

Review paperwork


(Passenger count)

(Load Sheet)g

Program FMC

Begin checklist

Checklist complete

Begin checklistChecklist completeENGINE START & PUSHBACK

Review paperwork

Sign flight release


Review FMC

Takeoff brief

Ask for checklist


CLEARANCE

Sample of Preflight errors

Omitted review of (SID) charts - distractions - speed violation on departure

Failed to program new departure - interruptions during preflight - discover after takeoff

Forgot to request updated PDC - distractions; misled because preflight already complete - take off with expired PDC

Skipped checklist item - interruption - push back with Seat Belt signs off

Omit requesting Load sheet - defer during preflight; ACARS inoperative - takeoff without load sheet

Omitted check of circuit breakers - busy with preflight; rushing - unable to start engine after pushback

Never finished review of maintenance log - interruptions - aircraft flown with “open” item in logbook

Checklist item read but not verified - interruption - pushback with emergency door slides armed

Entered wrong weight into FMS - tail strike at takeoff

Missed checking main tank fuel quantity - distractions - departed with insufficient fuel

Neglected to add MEL to flight release - multiple distractions, busy with preflight - discovered en route

Skipped over checklist item - interruption - departed without lobgook

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

Forgot to call maintenance - distractions - depart with hatch installed backwards

Forgot to request PDC - deferred when instructed to request by voice, not ACARS - discover after takeoff

Forgot to complete preflight flow - interruption - took off with APU running

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

Improper setting of pressurization during preflight flow - interruptions - cabin altitude warning light in cruise

Read but not verify checklist item - distractions - pushback with throttles open, damage to aircraft

Forgot logbook at ramp - kept deferring to check it; distractions; busy with preflight - discovered en route


Start checklist

• TAKEOFF

Start taxiing

Ask for checklist


Ask for checklist

Line up with runway

Failed to start engine #-2 - distracted while discussing special operations for destination; omitted checklists - delay takeoff

Omitted call for flaps -rushed to clear ramp/gate area for arriving aircraft -aborted takeoff

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

Omit above-line Checklist - running late, checklist interrupted by Tower, unexpected clearance for takeoff - abort takeoff

FO failed to monitor CA - busy checking and correcting calculations of load data - taxi past hold short line

FO failed to monitor CA – busy with flow; night taxi – taxi in wrong direction

CA taxied without having fully understood instructions - busy looking at other aircraft on taxiway and ramp - ground controller issued warning

FO failed to monitor CA - busy with pre-takeoff preparations - aircraft crossed hold short line

Flaps incorrectly set - late paperwork ; runway change; programming FMC; short taxi; rushed to accept takeoff clearance- aborted takeoff

Started taxi without clearance - trouble-shooting problem with engine start - nearly hit ground handler

Started taxi without clearance - crew discussing taxi instructions - struck pushback tug

Omitted flaps - checklist interrupted by Tower; crew rushed to accept takeoff clearance - aborted takeoff

Omitted flaps - checklist interrupted by thrust reverser light; crew busy troubleshooting - aborted takeoff

Misunderstood Tower instruction - new FO on IOE, CA coaching FO - taxi onto runway w/o clearance

Confuse own position on taxiway diagram - new terminal; studying NOTAMs; runway change – taxied into ditch

Started taxi without clearance – rushed by other aircraft waiting to pull into gate; radio congestion; marshaller’s headset inoperative – query by ground controller

Omitted checking reason for bleed air indicator light-busy with delayed engine start and checklists - takeoff without troubleshooting

Fail to confirm flap position - evaluating heavy rain showers; rushed to accept takeoff clearance - aborted takeoff

Neglected to set flaps -preoccupied with new departure clearance and packs-off operation -aborted takeoff

FO failed to monitor CA -runway change; busy reprogramming FMC -taxied past intended taxiway

Omitted checklist - busy with delayed engine start and checklists; rushed to accept takeoff clearance - flaps not set, aborted takeoff

Incorrect trim setting - checklist interrupted after item had been read but not verified - aborted takeoff

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICERSample of Taxi-out errors

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.

Why So Vulnerable to These Errors?

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

Automatic processing has enormous advantages but also

has serious vulnerabilities

Aft Overhead

Logbook/Gear Pins

PREFLIGHT Flow (B737-300 - as trained)

**

*

*

**

*

**

*

***

*

*

*

*

Aft Electronic

Center Instrument

Mode Control Panel

CaptainInstrument

First OfficerInstrument

Forward Overhead

Forward Electronic

ControlStand

Logbook/Gear Pins

**

* *

*

* *

*

*

*

**

*

Aft Overhead

First OfficerInstrument

ATISSlakfj aslkfj890Slkdfj 3409589Slkafj f095j 019Sa;lskdfjlLskd

LOADSlakfj aslkfj890Slkdfj 3409589Slkafj f095j 019Sa;lskdfjlLskd

Slkf9 9oy99SlkdfjA;slkg eri kgj skj 9

FLIGHT PLANSlakfj aslkfj890Slkdfj 3409589Slkafj f095j 019Sa;lskdfjlLskd SFAS ALSKFJ

XLKAF ALKDFJJ;AL

PAX CT107, 22, 53 WH

FUEL107, 22, 53 WHPDC

Slakfj aslkfj890Slkdfj 3409589Slkafj f095j 019Sa;lskdfjlLskd

Slkf9 9oy99SlkdfjA;slkg eri kgj skj 9

JEPP107, 22, 5

• •x

Forward Overhead

CaptainInstrument

Center Instrument

Forward Electronic

ControlStand

Aft Electronic

Mode Control Panel

CA flow FO flow

* Checklist item

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.

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.

Vulnerability to Errors of Omission Can Be Reduced

1) Actions airline operations and training departments can take

2) Actions individual pilots can take

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).




step that cannot be forgotten (e.g., pushback).

• Analyze actual fleet “norms” for how checklists are executed and bottom-lines observed.– LOSA




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

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.

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).

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.

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