Mode Awareness Problems in Advanced AutoFlight Systems

S. S. Vakil (sanj@mit.edu),

A. H. Midkiff (ahmidkiff@aol.com),

R. J. Hansman (rjhans@mit.edu)

Research Objectives

1. Investigate and identify major mode awareness problems in advanced AutoFlight Systems.

2. Identify candidate solutions, including the development of mode awareness augmenting displays.

3. Evaluate the effectiveness of candidate solutions.

Significance

The AutoFlight Systems in advanced aircraft have evolved to a state of considerable mode complexity. Based on the current evolutionary trends of aircraft automation, future aircraft will have even more complex operating modes. This complexity has become suspect in several recent incidents. Complex operating mode structures are also suspected to hamper pilot training and pilot understanding of AutoFlight Systems.

Approach

Preliminary investigations took three different methods:
1. Review of the Aviation Safety Reporting System (ASRS) for problems caused by aircraft automation.
2. Inventory of current AutoFlight Systems, with emphasis on the Flight Mode Annuciators (FMAs).
3. Focussed interviews were conducted with flight crews, simulator check airmen, and crews were observed during recurrent training. Based on this information, a candidate solution using a profile display was proposed.

Accomplishments

Preliminary results from the ASRS examination identified 63% of mode awareness problems as being related to the vertical domain.

A chart of these results is shown below:

The inventory of current AutoFlight Systems identified a lack of feedback in the vertical domain, which is more complex to control than the horizontal domain, leading to the vertical domain being more prone to serious mode related problems. Additionally, the most recent commercial systems are designed to maximize passenger comfort, which may reduce vestibular cueing for pilots. Focussed interviews highlighted the lack of underlying structure to AutoFlight Systems. This lack of structure creates difficulty for pilots and trainers in the development of consistent mental models. In the absence of simple mental models, pilots create their own ad-hoc models baselined from nominal aircraft operation which are of questionable use during high workload, exceptional situations.

A profile display designed to mitigate mode awareness problems has been functionally specified and several static versions have been created. An early dynamic display has been implemented on the ASL Advanced Part Task Simulator. Finally, an evaluation methodology has been created using short interactive scenarios on the ASL Simulator which highlight mode awareness problems in current aircraft. Airline pilots will watch a documented mode awareness problem occur and attempt to identify the consequences of the problem.

Current Activities

Work continues on fulfilling the remaining functional requirements of the profile display. The set of scenarios is being implemented. An undergraduate project to investigate vestibular cueing has begun.

Images (click on them to get a big version)

Following is a picture of the Electronic Vertical Situation Display (EVSD) in a Flight Level Change mode.

This is the EVSD in a VNAV path mode, with the middle loop altitude constraining the path.

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