Development of a Bio-Mathematical Crew Fatigue Model for Business Aviation Operators

Against the backdrop of the current aviation accident trend which poses human factor as their main cause, pilot fatigue is a pivotal issue which may jeopardize mission safety. At current times, the development of a Fatigue Risk Management System (FRMS) for Business Aviation Operators (BAOs) is not required by EASA, albeit already mandatory according to UK and FAA regulations. The aim of this paper is to present a Bio-Mathematical crew fatigue model which can assist BAOs in the creation of a proper FRMS, based on objective science-based biological models. The already challenging conditions linked to the evaluation of fatigue are compounded by the conditions which BAOs are affected by: 24-hour-a-day activities, night flights, irregular and unpredictable flight schedules, extended wakefulness and changes of time zone. Factors such as these challenge human physiology and can lead to performance-impairing fatigue and increased risks to safety. The lack of instrumental examination providing an objective value of fatigue status makes it difficult to get a complete picture of the crew’s mental and physical state. This paper describes the main underlying elements employed in the model creation and how the model has been adapted for BAOs specific requirements. The model is backed up by simple however effective algebraic relationships which take into consideration several influences leveraging pre-existing scales: prediction of alertness, cumulative fatigue duty time and sub-standard sleep quality.