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Exploring Communication Dynamics: Control and Verification

This next excerpt drawn from the San Juan accident (Excerpt 8.4) illustrates the use of the ‘challenge and response’ structure in formal communication and is an example of action control and verification. Three items in the workflow, numbered in parenthesis, are actions or events that must be verified so that the crew can agree that the flight is proceeding as planned.

Excerpt 8.4

FO: Flight attendant’s chimed (1) flight controls are checked (2).

C: Check.

FO: Rudder cam (3)?

C: Centred.

We can also see here the nature of aviation communication as a prescriptive code. Hutchins (1995) noted that task-related communication in complex social settings, especially with external agencies, is usually conducted via limited bandwidth media. In an attempt to reduce the risk of failure, communication takes place using defined protocols. This is apparent in Excerpt 8.5. The meaning of this exchange is embedded in a shorthand description of the current status of the aircraft (current altitude and next waypoint) and requires both parties to understand what ‘Juliet’ refers to - the current airport information - and that it is a formal requirement to be in possession of the latest information before commencing the approach.

Excerpt 8.5

C: San Juan Approach, Eagle 401 seven thousand direct Dorado

[Current status]

АТС: Eagle flight 401 San Juan Approach expect the ILS [Future goal]

runway one zero, descend and maintain six thousand. [Control]

C: Seven for six, Eagle 401 [Verification]

АТС: Eagle 401 you said that you have Juliet? [Verification]

C: Affirm.

АТС: 401.

The bulk of this interaction relates to verification of status, but the first transmission for АТС does include information about a future goal: ‘expect the ILS’. In this next excerpt (Excerpt 8.6), we can see how social modes of interaction can substitute for a prescriptive code. It occurs after the FO has just taken off. As the aircraft leaves the ground, it starts to drift to one side of the runway. Detecting the discrepancy through visual cues, the captain intervenes to keep the aircraft on the correct track. Instead of directing the FO to maintain the runway centre line, he phrases his intervention in a softer, social tone:

Excerpt 8.6

FO: Positive rate, gear up. [Control]

C: In transit [Verification]

C: Be careful of drifting like that.. ,’s a bad habit. [Control option]

FO: Yup. [Verification]

Communication, Option Selection and Decision-Making

In Excerpt 8.7, the aircraft is on late finals and has been cleared to land on Runway 08. Earlier, having been instructed to fly at 160 kts until the outer marker, the captain had arbitrarily told the FO to reduce speed to 120 kts and then increase to 140 kts. This was because the captain wanted to maintain separation behind the Boeing 727 ahead of them. Each action was, of course, a decision, but it also illustrates role ambiguity. Despite the instruction from АТС, the captain’s idiosyncratic interpretation of his role, and any associated freedom of action that flowed from it, resulted in a unilateral change that had consequences. The target speed for the approach was 104 kts. The checklist that contained the step that established the required approach speed had been missed earlier in the flight and so no benchmark had been agreed by the crew in advance. The intervention by the captain had left the FO in a non-standard configuration, and he was seeking clarification about how best to reconfigure the aircraft.

Excerpt 8.7

FO: You still want me to keep it up ... slow down to one twenty? [Option]

C: Nah... just do whatever you need. Just ya ya got traffic on [Option]

a five-mile final behind you anyway. You get too slow because it screws their sequence up [Current


FO: Ok [Verification]

C: Cause I’ve I slowed you up more than he wanted, so.....

you were you were about four miles behind ‘em [the B-727]

and there’s not very much wind [Current


FO: Ok [Verification]

C: And below his glide slope, which is a bad combination [Current


The FO’s utterance is an example of control action selection. Although too fast for the final approach, their option to reduce speed has been removed because they had been flying slower than the planned speed according to АТС, allowing the traffic behind to catch them up. The captain is rationalising his action in relation to the Boeing 727 and their relative position in the traffic pattern. He is engaged in knowledge-based behaviour in order to rapidly update the current status. The excerpt illustrates how different types of behaviour interleave. This episode is representative of action as a stream of events, each of which has a prospective effect on the ability to implement alternative future courses of action. By not following the instructions of АТС, future options have been constrained. The action now feeds forward to shape future actions. Similarly, sense-making can be retrospective. Having reached a point where a decision has to be made in relation to speed, the current status of the aircraft in relation to the desired goal state is being reviewed in the light of the past action. A conventional situational awareness analysis would argue that the captain failed to project ahead. In fact, he made a decision that made sense in the current context and in relation to his prior experience. To continue at the requested АТС speed, he would, in his opinion, have put the aircraft at risk of exposure to wake turbulence. His action made sense to him at the time. This whole episode is actually quite complex. For example, if we look at the propositional content of each utterance and the linguistic forms being used by the two speakers, we can question the effectiveness of the communication. However, I have limited the discussion to how decisions are embedded in communication.

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