Abstract
ObjectiveWe evaluated a variety of non-invasive physiological technologies and a series of test approaches for examination of aviator performances under conditions of mental workload in order to provide a standard real-time test for physiological and psychological pilot fatigue assessments.MethodsTwenty-one male aviators were selected for a simulated flight in a hypobaric cabin with artificial altitude conditions of 2400 meter above sea level. The simulated flight lasted for 1.5 h, and was repeated for two times with an intervening 0.5 h rest period outside the hypobaric cabin. Subjective criteria (a fatigue assessment instrument [FAI]) and objective criteria (a standing-position balance test as well as a critical flicker fusion frequency (CFF) test) were used for fatigue evaluations.ResultsNo significant change was observed in the FAI scores before and after the simulated flight, indicating that there was no subjective fatigue feeling among the participants. However, significant differences were observed in the standing-position balance and CFF tests among the subjects, suggesting that psychophysiological indexes can reflect mental changes caused by workload to a certain extent. The CFF test was the simplest and clearly indicated the occurrence of workload influences on pilot performances after a simulated flight.ConclusionsResults showed that the CFF test was the easiest way to detect workload caused mental changes after a simulated flight in a hypobaric cabin and reflected the psychophysiological state of aviators. We suggest that this test might be used as an effective routine method for evaluating the workload influences on mental conditions of aviators.
Highlights
Aviators are prone to experience physical and mental fatigue due to cabin noise, vibration, pressure changes, long flight durations, irregular working times and lack of sleep caused by above reasons, while fatigue seriously can affect flight operations of pilots
The subjective evaluation revealed no mental workload awareness of the subjects The fatigue assessment instrument (FAI) results of the subjects before and after the simulated flight showed that no significant differences of fatigue severity factors, environment-specific factors, outcome factors, or the rest and sleep-responding factors were stated between before and after trials (Table 1) were stated, indicating that no mental workload was recognized by subjective scales
The objective evaluating criteria revealed that changes of Steady Index’’ (ST), weight distribution and Critical flicker fusion frequency (CFF) resulted from the mental workload
Summary
Aviators are prone to experience physical and mental fatigue due to cabin noise, vibration, pressure changes, long flight durations, irregular working times and lack of sleep caused by above reasons, while fatigue seriously can affect flight operations of pilots. The severity of aviators fatigue symptoms are depending on the flight altitude, which can be divided into three levels: symptomless level (an altitude below 3000 m), compensatory level (3000–5000 m) and dangerous level (above 7000 m). The heart rate and pulmonary ventilation increases, indicating that the compensatory response of the human body develops some hypoxia adaption mechanisms at this altitude and symptoms are not serious if the period is short or the condition is in a stationary state, but even at the compensatory level mental functions and work abilities of aviators may already be affected [2]. The oxygen demand of the body cannot be satisfied by compensatory responses and mental and motor coordination dysfunctions occur after exposure to this area in a short time. Modern aircrafts generally are equipped with an automatic pressure regulation and in most airplanes the cabin atmospheric pressure can be adjusted to a pressure equivalent of 1500 to 2000 meters while the flight altitude is 9000 to 10000 meters above the sea level and a simulated flight in a hypobaric cabin with a 2400 m altitude atmospheric pressure is a close to reality model for studying mental workload of aviators
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