Modeling Different Function Allocations

Of special interest here is the representation of function allocations. Taskwork actions are assigned to different agents with each function allocation, and each function allocation also adds its own set of teamwork actions. Thus, while the overall structure of the taskwork, and the higher-level functions are the same throughout different function

86 allocations, the decisions made within them, and the assignment of teamwork and taskwork actions assigned to each agent, varies between function allocations.

The available function allocations in the flight deck were described in detail in Chapter 2. Table 9 briefly summarizes these function allocations.

Table 9. Function allocations modeled in the arrival-approach model

Function Allocation Description

FA1 Highly-automated function allocation

Pilot using LNAV/VNAV with air traffic instructions directly processed by the flight deck automation.

FA2 Mostly-automated function allocation

Pilot using LNAV/VNAV with pilot receiving air traffic instructions and programming the autoflight system.

`FA3 Mixed-automated function allocation

Pilot selecting the vertical autoflight targets and receiving air traffic instructions, and the FMS commanding the lateral autoflight targets.

FA4 Mostly-manual function allocation

Pilot selecting the autoflight targets and receiving air traffic instructions.

Consider the function allocation in which the pilot uses LNAV/VNAV with air traffic instructions directly processed by the flight deck automation (FA1). This function allocation is the most highly automated; thus, most of the taskwork actions are assigned to the flight deck automation. Table 10 lists the temporal functions for this function allocation in the first column, and actions within each temporal function are assigned to each agent, pilot and flight deck automation, as listed in the next two columns.

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Table 10. Function allocation 1: “Highly-automated” function allocation (teamwork actions in bold).

Temporal Function Pilot Automation

Control Vertical Profile

Modify CDU Pages

Reduce Airspeed for Late Descent Confirm Target Altitude Monitor Dist Active Waypoint

Calculate Dist Current Waypoint Evaluate Flight Phase Control Heading Monitor Heading Trends Update Lateral Control

Control Vertical

Evaluate VNAV Mode Transition Evaluate Alt Restriction Mode Altitude Reminder

Control Airspeed Monitor Descent Airspeed Update Thrust Control Calculate Speed Deviation

Turn off Altitude Alert Respond to Drag Required

On the other hand, Table 11 describes actions required for the mostly-manual function allocation in which the pilot is flying the aircraft by selecting the heading, airspeed, and altitude targets and autopilot modes using the MCP (FA4). Compared to FA1 shown in Table 10, the mostly-manual function allocation (FA4) does not require the human to perform teamwork actions such as “monitor waypoint progress.” Instead, many taskwork actions such as “manage waypoint progress” are shifted from the automation to the human. Also different teamwork actions such as dialing the altitude

88 selector have been added to the list due to the use of a different interface (i.e., MCP) in the flight deck.

Table 11. Function allocation 4: “Mostly-manual” function allocation (teamwork actions in bold).

Temporal Function Pilot Automation

Control Vertical Profile

Monitor Altitude

Reduce Airspeed for Late Descent

Control Waypoints Manage Waypoint Progress Direct To Waypoint Push Alt Hold Switch Push FLCH Switch

Push Vertical NAV Switch Push Vertical Speed Switch Monitor Green Arc

Turn off Altitude Alert Respond to Drag Required

The mostly-automated function allocation (FA2) is shown in Table 12. This function allocation is similar to the highly-automated function allocation (FA1) except that communicating with ATC is assigned to the pilot. Therefore, temporal actions such

89 as “receive altitude clearance” and “receive waypoint clearance” are allocated to the pilot.

Also, because the pilot executes these actions directly, the teamwork action “confirm data communication” is no longer needed.

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Table 12. Function allocation 2: “Mostly-automated” function allocation (teamwork actions in bold).

Temporal Function Pilot Automation

Control Vertical Profile

Modify CDU Pages Reduce Airspeed for Late Descent Monitor Dist Active Waypoint

Calculate Dist Current

Control Heading Monitor Heading Trends Update Lateral Control

Control Vertical Speed Monitor Altitude

Monitor Vertical Deviation Control Airspeed Monitor Descent Airspeed Update Thrust Control

Calculate Speed Deviation

Turn off Altitude Alert Respond to Drag Required

Lastly, the “mixed” function allocation (FA3), shown in Table 13, describes the function allocation in which the pilot executes actions relevant to managing the vertical profile (e.g., by setting altitude and speed targets in the MCP and commanding the appropriate autoflight modes to achieve them) while the flight deck automation executes

91 actions relevant to managing the lateral profile (i.e., lateral control via LNAV to follow the route programmed into the FMS using the CDU). Therefore, this function allocation is “mixed” between FA2 and FA4.

Table 13. Function allocation 3: “Mixed (using CDU and MCP)” function allocation (teamwork actions in bold).

Temporal Function Pilot Automation

Control Vertical Profile

Monitor Altitude

Reduce Airspeed for Late Descent

Control Waypoints

Manage Waypoint Progress Monitor Waypoint Progress Confirm Waypoint Target Monitor Dist Active Waypoint

Calculate Dist Current

Control Heading Monitor Heading Trends Update Lateral Control

Control Vertical Speed

Dial Altitude Selector Dial VS Selector Push Alt Hold Switch Push FLCH Switch

Push Vertical NAV Switch Push Vertical Speed Switch Monitor Green Arc

Turn off Altitude Alert Respond to Drag Required

92 5.1.3 Representing Pilot Cognitive Control Modes

In the arrival-approach model, three cognitive control modes are used to represent three patterns of behaviors: opportunistic, in which the pilot only responds to immediate needs in context, thus attempting only to “finish the job;” tactical, in which the pilot conducts monitoring and information seeking efforts as a part of procedures; and strategic, in which the pilot conducts monitoring and information seeking actions to anticipate upcoming needs.

Thus, in this arrival-approach model, these cognitive control modes determine how a pilot monitors the state of the aircraft and the environment, and how he/she prepares for the future taskwork actions as anticipated by some of the monitoring actions, as shown in Table 14. In the opportunistic mode, the pilot only executes the most essential monitoring actions such as “Monitor Altitude” and “Monitor Descent Airspeed.”

These monitoring actions are essential in that the outcomes of these actions initiate necessary taskwork actions such as deploying flaps or executing checklists. In the tactical mode, the pilot executes most of the monitoring actions including confirming the behavior of the automation as changes are entered into the MCP and CDU. In the strategic mode, the pilot executes all actions listed in Table 14. These include certain monitoring actions that attempt to respond to anticipated future states and, thus, to ameliorate impacts from the off-nominal events (e.g., if the descent clearance appears to be past due, reduce airspeed within the allowed margin of 0.02 Mach or request a lower airspeed).

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Table 14. Monitoring actions included within each cognitive control mode and their timing States Relevant to

the Action Actions of the Pilots Cognitive Control Mode Opportunistic Tactical Strategic States of Aircraft

Configuration Confirm Configuration Change Periodically Anticipated

Position

Monitor Altitude As required Periodically Anticipated Monitor Vertical Deviation Periodically Anticipated Monitor Distance to Waypoint Periodically Anticipated

Verify TOD Location Anticipated

Verify Crossing Restriction Anticipated

Monitor Green Arc Periodically Anticipated

Confirm Target Altitude Periodically Anticipated Confirm Target Airspeed Periodically Anticipated Direction

Monitor Heading Trends Periodically Anticipated Monitor Waypoint Progress Periodically Anticipated Confirm Active Waypoint Periodically Anticipated Speed

Monitor Descent Airspeed As required Periodically Anticipated Reduce Airspeed for Late

Descent Anticipated

States of Environment

Communication Confirm Data Communication Periodically Anticipated

Request Clearance Anticipated

Pilot cognitive control modes are further differentiated by how the pilot determines when to perform the actions. Actions are “anticipated” and thus scheduled more frequently (or targeted to future times of likely interest) when the pilot is in the strategic mode seeking to “notice” any changes in the states of aircraft and environment.

In contrast, those actions are scheduled “periodically” when the pilot is in the tactical mode, as if the pilot is executing a routine scan pattern.