Distributed Cognition How a Cockpit Remembers Its Speeds Edwin Hutchins

Classical Cognitive Science Thinking about thinking Mental processes Individual human agent How information is represented Transformed Combined Propagated Nature of knowledge

Distributed Cognition Unit of analysis Processes within system Representations External Internal

Cognitive Systems Organizations Role of material media Physical processes Human actors Material media Interactions Explicit nature of environment

Context: MD-80 Cockpit Representations inside cockpit system External to pilots Procedure = behavioral properties Constraint-based Workers-finish-design

Task: Memory Task Remembrance of speeds For subsequent use For proper & safe Initial descent Approach to land Instrument landing

Artifacts: Wing Shape

Artifacts: Speed Card & Fuel

Artifacts: ASI & Speed Bugs

Actors: Pilot Roles Two pilots/stations Complete dual-flight instrumentations Pilot Flying (PF) Pilot Not Flying (PNF)

[Cross-checks & verbal communication] Process Description Prepare landing data (20 - 30 min. out) Determine gross weight (Fuel Qty) Find correct speed card (2000 lb. incr) Post speed card Set speed bugs on both ASIs Descent - slow plane & configure wings Final approach to land - Vref [Cross-checks & verbal communication] At about 1,000 feet AFL, the crew will select the final flap setting of 28° or 40°, and maintain the approach speed. At 500 feet AFL, the PNF calls out the altitude, the airspeed relative to the approach airspeed, and the descent rate. For example, "Five hundred feet, plus four, seven down," meaning, 500 feet above the field elevation, 4 knots faster than desired approach speed, descending at 700 feet per minute. The pilot not-flying may also specify relation to the glide slope, indicating whether the airplane is below, on, or above the glide slope. Once final flaps are set on the final approach segment, the PNF calls out airspeed whenever it varies more than plus or minus 5 knots from approach speed.

Cognitive Description-External How are speeds represented? How are representations Transformed, Processed, Coordinated? How does the system’s memory work?

Observable Representations Gross-weight display (Fuel Qty) Speed card booklet ASIs & speed bugs Speed-select of Flight Director Verbal exchanges between pilots Setting bugs Cross-checks Call-outs /progress reports

Additional Representations Memory of each pilot Individual considered as part of system Media in the cockpit Task environment forms memory Internal representations

Speed Card & Gross Weight Long-term memory Gross weight Appropriate speeds Functionally durable Filtered information Correct weight = correct speeds Distributed access Social space Knowledge

Distribution & Transformation Transformations of representations Verbal (as relayed between PNF & PF) Via speed bug settings Cross-checking & redundancy Time-critical procedure indications

Configuration Changes Speed determined ATC instruction Position in approach ASI needle nears appropriate bug PF calls for flap/slat configuration PNF configures flaps/slats Verification & cross-checks (with speed card)

Salmon Speed Bug Final approach speed reference (Vref) Spatial relation with ASI needle PF to track speed PNF to determine deviations Verbal representation of call-outs Lightens demand on visual load of PF

External Representations Summary Speed bugs Resource for later processes Durable working memory Coordinated representations Verbal Speed card/fuel qty Configurations “System memory”

Cognitive Description-Internal Cognitive tasks of pilots Task specification Not procedural recount Provide constraints on useable Representations Processes Interpretation not recall Function in system memory

Speed Card & Gross Weight Pattern matching Implicit learning Internal structure for prediction Interpret values Card design Working memory Setting bugs - varied sequences

Configuration Change Bugs Numerical relations Spatial position Space of speeds “Configuration zones” Superimposing representations Functional systems

Configuration Zones

Salmon Speed Bug Numerical relation Scale of ASI and need positioning Spatial proximity Scale-reading task Base of salmon bug Verbal call-out - aural cue

Notion of Memory Traditionally a psychological function A series of tasks in a functional system Recognition & recall Pattern matching Cross-modal transformations Distributed Among human agents Between human agents Transformed external representations

Workers Finish the Design Provides constraints and artifacts Salmon bug Engineer’s design Ease of location Ease of interpolation Pilot’s use Determine 5-kt. deviations Not anticipated by designer (engineer)

Cockpit as Cognitive System Unit of analysis Transforms & propagates information Use of representations Notion of memory task Redundant & robust