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Maintenance of Underlying Skills with Extensive FMS Experience
Human Factors in Aircraft Automation - issue #6

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

One final issue discussed by the Subcommittee requires consideration beyond policy statements. We review it here to encourage member carriers to consider its broader implications while they discuss setting policy for operating FMS-generation aircraft. Billings (1997) has spoken of the potential of operators to become disengaged from the underlying processes that have been given over to automated systems, and described how that can result in reduced or in-ability to carry out those processes when the automated system is disengaged or disabled. To the extent that the operator must be able to carry out those processes in an abnormal or emergency situation, the underlying skills must be maintained. Applying that line of thought to pilots, we could expect those functions that are predominantly carried out by automated systems on an FMS-generation aircraft to suffer some skill loss. This might include hand-flying the aircraft in phases of flight were the autopilot is predominantly used, thrust control when autothrottles are disengaged, calculations of climb or descent targets or timing without FMS assistance, and continuous navigation by reference only to ground based navaids.

Supporting Evidence

Evidence of any change in such skills among Part 121 pilots is limited. What exists is based upon either anecdotal reports by Training departments or upon accident, incident, or event reporting and analysis. Member carriers have described possible examples including additional training required by First Officers with extensive FMS experience upon upgrading to Captain on less-automated aircraft (instrument scan and descent planning are frequently cited), activation — rather than deactivation — of autoflight systems in recovering from excursions from controlled flight in at least two accidents, and events in which pilots have assumed disengaged autothrottles were engaged and applied no thrust control as the aircraft accelerated or decelerated out of the desired flight envelope. In fact, whatever the assessment of supporting evidence, much of the emphasis in recent advanced aircraft maneuvering training has involved potential loss of flying skills and "automation dependency." It is clear that many member carriers have concluded that maintaining underlying skills is a challenge, with or without controlled scientific studies to back those beliefs.

But perhaps the best evidence for skill loss with extended use of autoflight and flight guidance/management systems has come from the recent decertification of Omega Navigation Systems. A surge in navigation deviations on aircraft formerly equipped with ONS and not yet equipped with GPS was observed in reports to Partnership Programs and NASA ASRS in late 1997. The source of these deviations was typically a failure of the pilot flying to tune and identify a new navaid, or select a new or correct radial on station passage, resulting in failure to make a required turn. Similar errors involving incorrect calculation of segment distances resulted in early course turns. These are basic functions of instrument navigation that were, until recently, assumed by ONS coupled to the autopilot. When that function was removed, pilots had difficulty in reapplying a well-learned and understood process they had performed throughout their careers. This is exactly the phenomenon Billings describes in more general terms.

Issues Requiring Member Carrier Review

Though the evidence is admittedly mixed, the Subcommittee is concerned about two issues — maintaining skills that remain necessary in FMS aircraft, and skills that are necessary when transitioning to a less-automated aircraft. Each of the following are potential concerns:

1. Assembly of situation awareness from disparate instruments rather than only from a map display remains a critical skill, but can become unexercised operating an FMS aircraft in a non-threatening environment. Map displays present valuable and key elements of situation awareness, but not all of them. For example, until the advent of EGPWS, no terrain information was displayed. Pilots have always been required to assemble position, course, and terrain information in some form of mental map described as situation awareness. With map displays, some but not all elements are automatically displayed or are pilot selectable. Do pilots routinely practice integrating non-displayed elements in non-threatening environments? This seems unlikely, and if not, represents a challenge to maintaining these skills. Such skill is occasionally critical, as in the case of a map shift, or in recovery from an inadvertent track deviation. Member carriers should look for opportunities to test and reinforce these skills in training and checking.
2. Instrument cross-check condenses toward the primary flight display on FMS-generation aircraft; more so with integrated primary flight displays. Cross-check of other instruments is necessary in certain phases of flight and this requirement broadens with certain types of approaches. This a direct challenge as member carriers attempt to resolve the raw data policy issues discussed above. Member carriers should act to assess and correct any scan problems during training and checking.
3. Similarly, with the known high reliability of FMS navigation, PNF monitoring skills may go unchallenged – if deviations are very rarely detected, the motivation to search for them naturally declines. But, the PNF must be as alert as the PF, regardless of level of automation available in the aircraft. A low probability, high criticality error is exactly the one that must be caught and corrected. Member carriers should assess and emphasize these skills.
4. Flight path management, though a key function of FMS, continues to require pilot judgment skill. For example, while calculating descents is automatic, the pilot must do so quickly in response to ATC-imposed crossing restrictions. This remains necessary because the validity of these clearances must often be assessed in less time than is required to set them up in the FMS. Otherwise, the pilot discovers that the opportunity to make the restriction passed while he and the FMS were calculating it.

The Subcommittee noted that at least one member carrier makes simulator time and instructors available to FMS-experienced FOs upgrading to Captains on analog aircraft, prior to the pilot beginning the scheduled training footprint. The subcommittee views this as one potential means for tackling this issue and encourages member carriers to develop alternatives.