Human Error Definition Broad Classes of Human Errors an occasion “… in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency.” James Reason Broad Classes of Human Errors Planning Failures: Mistakes inappropriate plan, misdirected intention plan carried out as intended e.g., wrong medication prescribed & administered Execution Failures Slips appropriate plan, intention part of plan performed incorrectly e.g., trocar injury Lapses part of plan omitted e.g., forget to remove sponge before closing

Understanding Human Error: The AORTA (Stage) Model of Human Performance Attend attend to one task attend to several tasks Remember Observe Think Act see/read hear feel (palpate) detect discriminate recognize perceive memorize recall (long-/short-term) maintain mental model calculate decide solve develop alternatives choose alternative select response reach grasp move/manipulate speak walk/run respond stimuli responses Environment

Some Common Human Fallibilities Attend limited attentional resources attraction to salient but irrelevant cues inability to focus attention: distraction inability to divide attention: tunneling Remember Observe Think Act stimuli responses Environment

Some Common Human Fallibilities Attend Remember Observe Think Act detection thresholds limited visual field sensory impairments auditory masking discrimination thresholds vigilance loss stimuli responses Environment

Some Common Human Fallibilities Attend Remember Observe Think Act limited working memory capacity (7 + 2 “chunks”) limited working memory duration (< 20 sec) inefficient chunking verbal/spatial dominance weak long-term memory associations stimuli responses Environment

Some Common Human Fallibilities Attend Remember Observe Think Act anchoring, confirmation bias recency bias tendency to treat all sources as equally reliable bias against absence of cues asymmetric valuation (gain/loss) overconfidence erroneous mental model stimuli responses Environment

Some Common Human Fallibilities Attend Remember Observe Think Act anthropometric limits neuromuscular limits strength limits response time considerations speed/accuracy tradeoff stimuli Environment

Rasmussen / Reason Model of Human Performance Skill-Based Rule-Based Knowledge-Based goal / problem recognized consider state info try to find analogy yes found ? familiar pattern ? no initiate “automatic” process with attentional checks no revert to mental model, analyze yes apply If-Then rule deduce, infer, plan, execute problem resolved ? problem resolved ? no no problem resolved ? no yes yes yes goal achieved

Reason’s Error Taxonomy (partial) Skill-Based Errors double-capture slips omissions (lapses) following interruption reduced intentionality (prospective memory errors) Rule-Based Errors first exceptions strong-but-wrong rules information overload wrong rule Knowledge-Based Errors selectivity working memory limitations anchoring / confirmation bias illusory correlation problems with complexity delayed feedback serial vs. network causality thematic vagabonding

Reducing Human Error in the Cockpit Universality of pilot error widely acknowledged. Most pilot error due to innate human fallibility. Contribution of pilot error to aircraft accidents well understood. Pilot error anticipated, prevented, mitigated. Countermeasures, e.g., pointer/counter altimeter moving “tape” altimeter moving map display checklists other mnemonics (memory aids) Crew Resource Management (CRM) training

Three-Pointer Altimeter

Pointer-Counter Altimeter

Moving Tape Altimeter

Moving Map Display

Checklists e.g., Boeing 757

Other Mnemonics (Memory Aids) Before-Landing Mnemonic: GUMPS Gas (fuel system configuration) Undercarriage (landing gear down) Mixture (engine fuel/air mixture) Props (propeller pitch) Systems (other system settings)

Crew Resource Management (CRM) Training Communication / Interpersonal Skills Situational Awareness Problem Solving / Decision Making / Judgment Leadership / “Followership” / Teamwork Task Management Stress Management Critique