On the Design of Flight-Deck Procedures - Intelligent Systems ...

3. The procedures allow the other agent(s) to plan and schedule their own actions/tasks in parallel tothe procedure(s).4. They set a defined standard of performance that allows all crew members to continually comparetargets (inputs) with actual performance, thereby providing all crew members with a baseline forquestioning and correcting substandard performance on part of other crew members.Feedback. SOPs specify expected feedback to other crew members (e.g., callouts). This feedbackcan detail (1) the current, and/or expected system state; (2) the actions that are currently being conducted;(3) the system outcome; and (4) an indication of task completion.There are several ways in which this feedback is provided: (1) verbally (callouts, callback, etc.); (2) nonverbally(gestures, manual operation -- such as pulling down the gear lever); (3) via the interface (whenthe configuration of the system is significantly changed, e.g., all CRT's are momentarily blank whenpower is switched from APU to engine-driven generators, this provides clear feedback to the other pilot);and (4) via the operating environment (when slats/flaps are extended during approach, there is a clearaerodynamic feedback -- pitch change).Information transfer. Procedures convey, or transfer, information from one agent to others. Indesigning tasks, procedures, and callouts, the designer must make sure that no information is lost andthat no noise 14 is added into information channel. Care must be taken with specifying non-verbal (paralinguistic)communication, as this form is usually less precise, difficult to standardize, and subject tomisinterpretation (Wiener, 1993). Noise can be added when an ATC call, or a flight attendant, interruptsintra-cockpit communication during high workload periods. One system goal is that the same amount ofinformation that is sent by one agent will be received by the other agent. When procedural requirementsare violated by the agent transmitting the information, e.g., the example of the first officer's takeoffcallouts of “V one- r, two of 'em” (Section 3.2.1), one can say that another form of unwanted noise (adeviant callout) has entered into the system.Why are these attributes important? Because the designer may want to consider them while designing aprocedure for a certain task. The procedure designer should design the feedback and informationtransfer aspects of the procedure in a way that will accommodate the requirements of the task. Forexample, if the designer decides that a procedure is critical (e.g., CAT II approach), he or she maydecide to employ all possible forms of feedback into the design in order to safeguard crew coordination.As for information transfer, understanding how information can become distorted allows the designer toprovide safeguards to reduce their likelihood of occurrence. The procedure and the other tasksconducted at the same time should be designed so as to minimize noise and losses. For example,information can be lost when a completion call, such as “the after takeoff checklist is complete,” ismumbled by the PNF. In our previous study we recommended that the completion call of the checklistshould be made an item in the checklist (Degani and Wiener, 1990).Each of the above forms of noise, when introduced into the system independently, would probably notlead to a sub-optimal performance. But as it usually happens in a system accidents, the interactionbetween several of such sources of noise (e.g., a not-per-SOP rotation callout and an interrupting ATCcall) and possibly other active failures (e.g., engine failure during rotation) may lead to sub-optimalperformance (Perrow, 1986; Reason, 1990). The designer cannot foresee each possible combination ofdistraction and unwanted interaction. The designer has no choice but to laboriously contain each sourceof noise independently. When the source is internal to the aircraft and company, containment is notdifficult (e.g., sterile cockpit rule), but if it is external (e.g., ATC), it is far more difficult to control.The issues of reducing variance and enhancing feedback and information transfer allows us to analyzethe interaction between critical tasks and technique via the eyes of CRM. When the aircraft is in a criticalphase of flight, such as during approach or takeoff, there is no time to be creative with individualistictechnique. At that point it must be strictly procedural -- not even a slight ambiguity among the crew howthe task is conducted. Procedures minimize variance in pilot performance and therefore allow the other14 Note that in this section we are using the term noise in the electrical engineering sense -- meaning anything thatdistorts or degrades the signal or information.36