Key DismukesChief Scientist for Aerospace Human Factors

Human Factors Research and Technology Division

NASA-Ames Research Center

ATA AQP Annual Conference

October 2003

Managing Interruptions, Distractions and Concurrent

Task Demands

Our Research Team• Immanuel Barshi• LaQuisha Beckum• Sean Belcher• Rahul Dodhia• Jon Holbrook• Kim Jobe• Tri Li• Loukia Loukopoulos• Jessica Lange Nowinski• Mark Staal

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: Flaps/slats not set to take-off position

• Dallas (1988): B-727 crashed shortly after take-off

– NTSB: Flaps/slats not set to take-off position

• Houston (1996): DC-9 landed gear-up

– NTSB: Hydraulic 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)

• 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 delays• But for luck any of these incidents might have become accidents

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.

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 depiction 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

Prepare/review charts

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

• Tasks are serial and linear: task A task B task C in a fixed sequence.

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

Prepare/review charts

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.

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

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

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

Receive takeoff clearance

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)

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.

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 paperworkSign flight releasePrepare/review charts

Review Load Schedule

Review FMC

Takeoff brief

Ask for checklist

Ask for checklist

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICER

CLEARANCE

procedure

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone

Ground/Company/Dispatch

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

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 paperworkSign flight releasePrepare/review charts

Review Load Schedule

Review FMC

Takeoff brief

Ask for checklist

Ask for checklist

CAPTAINCAPTAIN FIRST OFFICER FIRST OFFICER

CLEARANCE

procedure

Cabin Attendant

Gate Agent

ACARs / OPC

Interphone

Ground/Company/Dispatch

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

– 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.

– Lack of guidance

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.

ERRORS attributed to concurrent task demands, interruptions, and disruptions (ASRS reports)

Omitted review of charts - distractions - speed violation on departure Entered wrong weight in FMS - tail strike at takeoff

Omitted flow and checklist items - interruptions; delay; change in departure runway - discover insufficient fuel at 12000 ft

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

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 setting flap - busy with delayed engine start; rushed to accept takeoff clearance - aborted takeoff

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

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

Failed to verify new clearance - monitoring convective activity on radar - flew wrong heading

Omitted climb checklist - busy copying hold instructions - missed setting altimeter and overshot altitude

Failed to reset bleeds on - complex departure; multiple ATC calls; traffic - altitude warning and 0 2 mask deployment

Did not notice wind - preoccupied with annunciator light; handling radios - track deviation

Unstabilized approach - accepted runway change right before FAF; did not review charts or make callouts - tailstrike

Did not complete checklist - TCAS alerts; parallel runways in use; GPWS alert - did not extend gear for landingDid not extend gear; checklist interrupted; TCAS alerts; parallel runways in use; GPWS alert - struck ground on go-around

Forgot to reset altimeters - distracted by FA in cockpit - TCAS RA and overshot arrival fix

Failed to monitor PF - busy reprogramming FMS; weather changes - go around

Failed to verify FMC settings - PNF giving IOE to PF; multiple ATC calls; hold instruction - flew pattern in wrong direction

ATC instructions too close to turn fix - busy slowing aircraft; approach checklist; radios - failed to make published turn

Vectored too close - busy catching up with glideslope; not instructed to switch to Tower - landed without clearance

Forgot to switch to Tower at FAF - last minute runway change; busy reconfiguring aircraft - landed without clearance

PR

EF

LIG

HT

> P

US

HB

AC

K >

TA

XI >

TA

EK

OF

F >

CL

IMB

> C

RU

ISE

> D

ES

CE

ND

> L

AN

D

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 (B73-300 - as trained)(checklist items are marked *)

**

*

*

**

*

**

*

***

*

*

*

*

*

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

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).

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).

• 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 (e.g. checklist in

throttle quadrant)

• 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 (e.g. checklist in throttle

quadrant)

• 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.