Mode Awareness

As more systems are introduced into the cockpit and integrated with other systems, the potential grows for pilots to become confused about what the automation is doing. There is growing evidence that this phenomenon, often referred to as mode confusion or mode awareness, has played a significant role in many aviation accidents.

The MT-FCS project addresses mode awareness in three ways:

1. By combining the executable model of the requirements with a simulation of the flight deck, engineers, pilots, and experts in human factors can review the design while executing common scenarios. This interaction provides invaluable feedback to all parties on possible sources of mode confusion.
2. The models can be searched for patterns that are known sources of mode confusion with automated tools. For example, it is possible to detect any states in which an input by the flight crew has no visible effect on the flight deck.
3. Scenarios provided by the pilots can be written as partial specifications and checked against the behavioral model to determine whether they are actually true.

The MT-FCS project used these techniques to investigate the mode logic of a Flight Guidance System and its interaction with the vertical navigation (VNAV) function of the Flight Management System. Several enhancements suggested by this study have been incorporated in new products.

Publications Related to Mode Awareness

• Steven P. Miller, FMS Visualization Final Report, NASA Contractor Report, February 2004.
• Anjali Johsi, Steven P. Miller, and Mats P. E. Heimdahl, Mode Confusion Analysis of a Flight Guidance System Using Formal Methods, in Proceedings of the 22^nd Digital Avionics Systems Conference (DASC’03), Indianapolis, Indiana, Oct. 12-16, 2003. Selected as best paper of the Intelligent Interactive Systems-1 session.
• Steven P. Miller, Sarah Barber, Timothy M. Carlson, David L. Lempia, and Alan C. Tribble, A Methodology for Improving Mode Awareness in Flight Guidance Design, in Proceedings of the 21st Digital Avionics Systems Conference (DASC'02), Irvine, California, Oct. 27-31, 2002. Selected as best paper of the Software Engineering for Human Systems session.
• Steven P. Miller, Taxonomy of Mode Confusion Sources - Final Report, NASA Contractor Report, Feb 2002.
• Steven P. Miller, FGS Model Visualization - Final Report, NASA Contractor Report, Feb 2002.