Physiological and hygienic evaluation of the vibrations in a transport helicopter cockpit

In the cockpit of five helicopters the floor and the chair vibrated in a band of 8 Hz at a frequency of 112.5 and 114.0 dB, respectively. Before and after the flying shift 66 crewmembers were interviewed and examined. Vibration was referred to as the most unpleasant factor by 30.4% of them, noise was defined as the most unpleasant factor by 6.5% of them; 63.1% described both factors as similarly adverse. The level of psychophysiological changes was proportional to the flight time. The first signs of fatigue were seen after flights of up to 5 hours in duration to increase drastically after flights of 6 and 7 hours.