Instrument flying performance after G-induced loss of consciousness

While both the USAF and the USN have characterized the immediate sequelae of G-induced loss of consciousness (G-LOC) as resulting in approximately 24 s of incapacitation, very little is known about the effect of a G-LOC immediately after this incapacitation period. This study is an attempt to determine the effect of G-LOC on instrument flying performance immediately after G-LOC.

In order to establish their flying performance baselines, 29 Canadian Forces (CF) pilots attending the high sustained G (HSG) course flew 3 iterations of a 15-min instrument flying task on the day prior to their HSG course. All 29 pilots performed this same task the next day within 5 min of completing the centrifuge training. In addition, the pilots who experienced G-LOC flew the task again 45 min after G-LOC. Flying performance was assessed by calculating Root Mean Square (RMS) error on 11 flight parameters. These RMS values were submitted to a multivariate analysis of variance.

Of the 29 pilots, 12 experienced G-LOC during the centrifuge training. The flying performance of the 17 non-G-LOC pilots was not affected by their exposure to HSG. Of the 12 G-LOC pilots, 11 had no measurable performance decrement while 1 pilot, after a severe G-LOC, stalled and "spun-in" on take-off and then (after being re-established on the outbound radial) could not complete the task. This same pilot flew the task very well 45 min later. This study did not identify a degradation in flying performance after HSG nor after G-LOC except in the 1 pilot.

Whether or not a pilot's flying performance is affected after G-LOC may be related to the severity of the G-LOC. Some pilots may experience seizure activity relating to the G-LOC with a resulting sustained performance decrement that appears to resolve by 45 min. It is possible that some of the other G-LOC pilots in the study might have had measurable performance decrements if we had been able to have them fly the task while they were still in the gondola (i.e., immediately after the G-LOC).