Two Men in a Cockpit: Casualty Likelihood if One Pilot Becomes Incapacitated

摘要

A double-exponential probability distribution function of the extreme-value-distribution type is introduced to quantify the likelihood of a human's failure to perform his/her duties when operating a vehicle: an aircraft, a spacecraft, a boat, a helicopter, a car, etc. As a possible illustration of the general concept, a situation is considered when two pilots operate an aircraft in an ordinary (normal, routine) fashion that abruptly changes to an extraordinary (offnormal, hazardous) one if one of the pilots becomes incapacitated for one reason or another. Such a mishap is referred to as an accident. Because of the accident, the other pilot, the pilot in charge, might have to cope with a higher mental workload. A fatal casualty will occur if both pilots become unable to perform their duties. Although this circumstance will eventually manifest itself only during landing, in order to assess the probability of the potential casualty, an en route situation (i.e., a situation that precedes descending and landing) is nonetheless considered. This probability depends on the capability of the pilot in charge to successfully cope with the increased mental workload. We determine the probability of a casualty as a function of the actual mental-workload level and the level of the human-capacity factor. The total flight time and the time after the accident are treated in the analysis as nonrandom parameters. The suggested mental-workload/human-capacity-factor model and its generalizations, after appropriate sensitivity analyses are carried out, can be helpful when developing guidelines for personnel training, when choosing the appropriate flight simulation conditions, and/or when there is a need to decide if the existing level of automation and the navigation instrumentation and equipment are adequate to cope with extraordinary (offnormal) situations. If not, additional and/or more advanced instrumentation and equipment should be considered, developed, and installed. Plenty of additional risk analyses and human-psychology-related effort will be needed, of course, to make the guidelines based on the suggested probabilistic risk-management extreme-value-distribution model practical.