Lessons from Aviation: Memory, Skilled Human Performance, and All-too-human Error

1. Lessons from Aviation: Memory, Skilled Human Performance, and All-too-human Error Key Dismukes, PhD Chief Scientist for Aerospace Human Factors NASA Ames Research Center 12 January 2002

2. Road Map of Talk • A cognitive perspective on error   vulnerability of skilled professionals • Examples from one domain of error:   prospective memory • Lapses in everyday life • Lapses in flight operations • Implications for professional training

3. Most Airline Accidents Attributed to Crew Error • Society: error = blame • Misrepresents nature of cognitive skill • Undercuts safety • Research on human factors in aviation safety • Extrapolate to other professional domains?

4. Aircrew Performance • Trained to high level of performance; daily practice; annual recurrent training • Monitored periodically by check pilots • Highly motivated • NTSB accident reports reveal few examples of incompetence or malfeasance

5. Two Fallacies about Error Fallacy: Error can be eliminated if pilots are sufficiently  vigilant, conscientious, and proficient. Truth: Vigilant, conscientious experts routinely make errors. Fallacy: If an accident crew made errors in tasks that pilots routinely handle without difficulty, that accident crew must have been in some way deficient — either they lacked skill, or had a bad attitude, or just did not try hard enough. Truth: The fallacy ignores sampling bias. No matter how many times an expert performs a procedure perfectly, the probability of error is greater than zero.

6. A Cognitive Perspective • Simply trying hard will not prevent errors • Unique human capabilities enabled by biological information-processing mechanisms • Vulnerable to error • Error is probabilistic, not deterministic • Illustrate with research on memory errors

7. Prospective Memory (PM) • Remembering to perform an action that  must be delayed • Relatively new field of human memory  research • Defining characteristics: • Delay between forming intention and opportunity to   execute (seconds to years) • Delay filled with other tasks that occupy attention • No explicit prompt telling us it is time to execute intention • So how do we ever remember to perform   intentions? • A theoretical perspective

8. Attributes of the Model Focal Attention • Very limited capacity • Currently attended representations • Dynamic flow of contents • Representations compete to enter • attention based on level of activation External Stimuli More accessible Activated representations Activation Memory • Long-term memory • very large capacity Less accessible

9. animal racing Indian saddle cowboy “horse” Attributes: Activation and Retrieval of Memory Representations Focal Attention External Stimuli horse “horse” • Currently attended representation provides activation to associated item in memory • Activation increases as function of time in attention • Activation decays as function of time since last attended • Activation is finite and divided among associates • Activation is divided according to strength of links to associate More accessible More accessible Activation Memory Less accessible Long-term memory

10. Attributes: Goals are Memory Representations Focal Attention External Stimuli prepare vuegraph • Deferred intentions are a form of goal • Goals are represented as condition/action associates (If…then) • Goals are associated in hierarchies of sub-goals • Sub-goal in focal attention helps maintain activation of higher goal More accessible prepare talk More accessible Activation schedule conference room Memory Less accessible win Nobel prize floss daily Long-term memory

11. Einstein-McDaniel PM Paradigm • Instruct subjects to perform cover task   (e.g., reading a paragraph or rating pleasantness of   series of words) •   Give additional (PM) task   (e.g., “Press slash key when see a name of an animal”) •   Subjects begin performing cover task •   Delay between starting cover task and trial with   animal name •   Must remember to perform PM task without   prompting

12. cat Africa cub lion Prospective Memory as Competing Concurrent Task Focal Attention External Stimuli lion lion • Prospective task competes with pleasantness rating for retrieval • On-going task has inherent advantage • Outcome is probabilistic • Depends on multiple factors rate pleasantness animal More accessible press key More accessible Activation Memory Participate in experiment Less accessible Long-term memory

13. Implications for Real-World Performance • 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

14. Strategies • Importance of delayed intention does not   prevent memory lapses • Simply trying harder is ineffective • Strategies may help to some degree: • Habitual review: what do I need to do now? • Encode environmental cues likely to be present in window of opportunity for execution • Create salient cues that must be processed during ongoing task

16. Flight Crews Manage Multiple Tasks Concurrently • Cockpit operations are highly proceduralized • Taxi, climb out, descent, and arrival are sometimes quite busy • Each pilot is responsible for multiple concurrent tasks (e.g., searching for traffic and flying the airplane) • Interruptions, distractions, or preoccupation with one task to the detriment of another found in nearly half of NTSB accident reports • Issue may be management of attention rather than overload

17. Aviation Incident Study Examples of Neglected Tasks • Lapses in monitoring (2/3 of reports) • Aircraft position: taxi, altitude capture, navigation • Aircraft status: systems, automation • Actions of other crew member • Lapses in prospective memory (1/4 of reports) • Complete interrupted procedure on checklist • Retract speed brakes when leveling-off descent • Reset flaps and bleed air after de-icing • Stop fuel transfer • Set take-off flaps when deferred • Defer lowering landing gear in minimum fuel situations

18. Aviation Incident Study Competing Tasks that Distracted or Preoccupied Pilots • 50% involved communication (e.g., conversation with other crewmembers/flight attendants, radio communication, ATIS, PAX announcements). • 16% involved “head-down” tasks (e.g., paperwork, FMS entry, reviewing charts) • 14% involved abnormals • 8% involved searching for/responding to traffic • 12% miscellaneous (e.g., decision-making, unstabilized approach)

19. Aviation Incident Study Examples of Neglected Tasks • Lapses in monitoring (2/3 of reports) • Aircraft position: taxi, altitude capture, navigation • Aircraft status: systems, automation • Actions of other crew member • Lapses in prospective memory (1/4 of reports) • Complete interrupted procedure on checklist • Retract speed brakes when leveling-off descent • Reset flaps and bleed air after de-icing • Stop fuel transfer • Set take-off flaps when deferred • Defer lowering landing gear in minimum fuel situations

20. Omitting a Procedural Step • Highly practiced procedures vulnerable to omission when: • Interrupted • Performed outside normal sequence or context • Highly practiced procedures become largely automatic • Allows fast, smooth execution • Requires minimal conscious supervision • Execution largely under control of environmental cues • Most common error in maintenance: omitting a step in re-assembly • Example: finish tightening spark plugs

21. Omitting a Procedural Step Why So Easy to Forget a Procedural Step? • With highly practiced procedures, retrieval of each step triggered by: • Current state of environment • Execution of immediately preceding step • Interruption breaks chain of preceding steps -- no trigger • Environment may seem to indicate uncompleted step has been performed • No episodic memory trace for habitual actions

22. Training Implications Prospective Memory Countermeasures • Recognize the threat • Vulnerable even when tasks are important and delays are short • Especially vulnerable: Interruptions and performing habitual procedures out of normal sequence • Explicitly note interruption and identify when/where intention will be executed • In team situation, say aloud • Create salient reminder cues* • Avoid rushing procedures • Periodically review status and ask if anything is missing • Use checklists* * Not always practical

23. Training Implications Line Oriented Flight Training (LOFT) • Full-mission simulation • Normal operations and challenging situations (e.g., weather diversions, equipment failures) • Should include realistic: • Concurrent task demands • Interruptions • Distractions • Delays

24. Training Implications Error Management Training • Change in historic attitude • Errors are inevitable • Training should address: • Recognizing potential threats • Detecting errors • Managing error outcome

25. Training Implications Error Data from Routine Operations • What errors occur, circumstances, and how professionals respond • Accident/incident reports useful but are a limited and biased sample • LOSA: Line Operational Safety Audits • Large sample of daily operations • Data on threats, errors, and how crews manage • Comprehensive and realistic picture of challenges • LOSA + laboratory research   powerful new approaches to training