Ejection performance of strike pilots: effect of the designated decision height

This study investigated a proposal of the Royal New Zealand Air Force to lower its designated ejection decision height (EDH) of 10,000 ft above ground level (agl) so that pilots had more time to make a correct and timely ejection decision. Hypothesis Lowering the EDH will result in pilots adhering to the prescribed height for ejection and enable them to maneuver the aircraft into a profile more conducive to safe ejection.

Thirty male strike pilots each flew 20 simulated sorties. Half the sorties involved scenarios that required ejection and half did not. The pilots were divided into three equal groups that were randomly assigned to an EDH of 10,000, 6000, or 3000 ft agl.

Analysis was restricted to incorrect ejections. The mean height of ejection, although significantly related to the EDH (as expected), nevertheless was lower than the EDH for all three groups. Furthermore, the percentage below the EDH of the mean ejection height was approximately 28%, and not significantly related to the EDH. This constant percentage was interpreted in terms of Weber's Law. At the point of ejection, the aircraft for all three groups had generated very high rates of descent and low nose attitudes.

A significant number of pilots ejected below the EDH. Pilots perceived a constant percentage of the EDH, rather than an absolute value, as the critical height for ejection. A high rate of descent, coupled with a nose-low attitude, prevailed at the point of ejection, independently of the EDH.