Visual symptoms and G-LOC in the operational environment and during centrifuge training of Turkish jet pilots.
BACKGROUND
High-performance fighter aircraft produce high-sustained +Gz forces with rapid onset rates. Because of this G-producing capability, military jet pilots are subjected to physiological stress, which may lead to visual disturbances and G-induced loss of consciousness (G-LOC). Although visual disturbances are very common in jet flights, G-LOC is relatively rare but more dangerous. The frequency and causes of G-LOC need to be determined in the interest of flight safety.


METHODS
Part I. A survey was conducted on Turkish jet pilots to reveal the incidence of symptoms due to +Gz acceleration. Anonymous questionnaires were given to F-16, F-4, and F-5 pilots. They consisted of inquiries about the occurrence of visual symptoms and/or G-LOC during +Gz acceleration in the operational environment. Part II. During the years 1992-1996, 486 F-16, 801 F-4, and 256 F-5 fighter pilots underwent high "G" training at Turkish Aerospace Medical Center and they were assessed in terms of G-LOC rates.


RESULTS
Part I. A total of 325 pilots who flew T-37 in undergraduate pilot training (UPT) answered the questionnaire. The pilots were divided into 3 groups according to the types of aircraft, which they fly now: 116 F-16, 182 F-4, and 27 F-5 pilots. A total of 311 pilots (95.7%) reported having experienced greyouts and/or blackouts. With 25 pilots (7.7%) experiencing G-LOC, the G-LOC frequency according to the type of aircraft was: 5.2% (T-37) [in UPT]; 4.3% (F-16), 1.6% (F-4), and 0% (F-5). Part II. In centrifuge training, the incidence of G-LOC in pilots of the various types of aircraft were: 12% (F-16), 6.4% (F-4), and 8.6% (F-5).


CONCLUSIONS
Centrifuge training reduces G-LOC rates of subsequent centrifuge training; and it is hoped might reduce the G-LOC rate in the operational environment. Almost all jet pilots reported having experienced +Gz related visual symptoms, but G-LOC seems to be a more common problem for pilots who fly rapid onset rate aircraft than pilots who fly high "G" capable but lower G onset rate aircraft.
GATA, Aerospace Medical Center, Eskisehir, Turkey.
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Yilmaz
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M
Cetinguc
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Akin
D000054:Acceleration / Q000009:adverse effects*; D000337:Aerospace Medicine; D000401:Aircraft / Q000145:classification; D002498:Centrifugation / Q000009:adverse effects* / Q000379:methods* / Q000639:trends; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D007318:Inservice Training / Q000379:methods* / Q000639:trends; D008889:Military Personnel / Q000193:education; D009784:Occupational Diseases / Q000209:etiology* / Q000517:prevention & control*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D014421:Turkey; D014474:Unconsciousness / Q000209:etiology* / Q000517:prevention & control*; D014636:Valsalva Maneuver; D014786:Vision Disorders / Q000209:etiology* / Q000517:prevention & control*