'Two Men in a Cockpit': Assessment of the Likelihood of a Casualty if One of the Pilots Becomes Incapacitated

摘要

We introduce a double-exponential probability distribution function (PDF) of the extreme value distribution (EVD) type to quantify the likelihood of a human failure to perform his/her duties, when operating a vehicle: aircraft, spacecraft, boat, helicopter, car, etc. We consider, as a possible illustration of the general concept, a situation when two pilots operate an aircraft in an ordinary (normal, routine) fashion, which abruptly changes to an extraordinary (off-normal, hazardous) one, if one of the pilots becomes, for one reason or another, incapacitated. Such a mishap is referred to as an accident. Because of the accident, the other pilot, "pilot-in-charge" (PIC), might have to cope with a higher mental workload (MWL). A fatal casualty will occur if both pilots become incapable to perform their duties. Although this circumstance will eventually manifest itself only during landing, we nonetheless consider an en-route situation, i.e. a situation that precedes descending and landing, to assess the probability of the potential casualty. This probability depends on the capability of the PIC to successfully cope with the increased MWL. We determine the probability of a casualty as a function of the actual MWL level and the level of the human capacity factor (HCF). The total flight time and the time after the accident are treated as non-random parameters. We believe that the suggested MWL/HCF model and its generalizations, after an 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 existing navigation instrumentation and equipment are adequate in extraordinary (off-normal) situations. If not, additional and/or more advanced instrumentation and equipment should be 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 (PRM) EVD model practical.