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Improving ATC Procedure Compatibility with FMS-Generation Aircraft
Human Factors in Aircraft Automation - issue #5

SECOND REPORT from the Human Factors Committee, Automation Subcommittee, Air Transport Association

Two issues involving ATC were raised in the FAA Human Factors Team report or in the deliberations of the subcommittee: Last-minute runway, departure, or approach changes are a frequent source of increased workload and error on FMS aircraft. A number of ATC procedures fail to take advantage of FMS capabilities or are structured in such a way as to interfere with their use.

Supporting Evidence

Regarding last-minute runway, departure, or approach changes, member carriers represented on the subcommittee provided a number of examples of errors resulting from pilots attempting to comply. Part of the problem — rushing to comply — generalizes to non-FMS aircraft. What is unique is an ambiguity of how to set up navigation for such a change. Should the pilot attempt to use the FMS first when a change is issued? It provides course guidance for many departures and for approaches and missed approaches along with access to the required navigation frequencies. Alternatively, since reference to ground-based navigation is required, should it be completed first? The subcommittee noted several reports where pilots made significant errors, including not tuning the required navaids in the rush of such a change.

Regarding ATC procedures that are not compatible with FMS aircraft, there appear to be a number of enhancements possible to existing ATC procedures that would directly benefit these aircraft without creating special procedures and without decrement to non-FMS aircraft. In general, the FMS is of little help for vector SIDs. Selection of the JFK7, for example may result in no legs appearing on the legs page or on the Map display, depending on the runway and whether there is a common point for all climbs or transitions from that runway after takeoff. This results in a very complex departure that must be built, rather than selected, if the pilots wish to use the FMS. In the short term, establishment of a standard, or default, vector or radial associated with each fix from which the departure is exited, would greatly reduce workload in the departure phase and make navigation errors less likely.

Policy Guidance for Pilot Action

Further guidance to pilots on response to ATC clearance changes in the terminal area is warranted. The subcommittee offers the following prototypical statement for publication in policy manuals:

Additional Actions

The Subcommittee recommends that the ATA Air Traffic Management Committee initiate discussions on developing enhancements to ATC departure and arrival procedures, especially including vector SIDs, to benefit operation of FMS aircraft.