Citation

McMahon TW, Newman DG. Mil. Med. 2016; 181(11): e1696-e1699.

Affiliation

Griffith Aviation, School of Natural Sciences, Griffith University, Nathan Campus, 170 Kessels Road, Nathan, Queensland, 4111 Australia.

Copyright

(Copyright © 2016, Association of Military Surgeons of the United States)

DOI

10.7205/MILMED-D-16-00073

PMID

27849510

Abstract

INTRODUCTION: Military helicopters are increasingly agile and capable of producing significant G forces experienced in the longitudinal (z) axis of the body in a head-to-foot direction (+Gz). Dehydration and fatigue can adversely affect a pilot's +Gz tolerance, leading to +Gz-induced symptomatology occurring at lower +Gz levels than expected. The potential for adverse consequences of +Gz exposure to affect flight safety in military helicopter operations needs to be recognized. This case report describes a helicopter pilot who experienced +Gz-induced visual impairment during low-level flight. CASE STUDY: The incident occurred during a tropical training exercise, with an ambient temperature of around 35°C (95°F). As a result of the operational tempo and the environmental conditions, aircrew were generally fatigued and dehydrated. During a low-level steep turn, a Blackhawk pilot experienced significant visual deterioration. The +Gz level was estimated at +2.5 Gz. After completing the turn, the pilot's vision returned to normal, and the flight concluded without further incident.

DISCUSSION: This case highlights the potential dangers of +Gz exposure in tactical helicopters. Although the +Gz level was moderate, the pilot's +Gz tolerance was reduced by the combined effects of dehydration and fatigue. The dangers of such +Gz-induced visual impairment during low-level flight are clear. More awareness of +Gz physiology and +Gz tolerance-reducing factors in helicopter operations is needed.

Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Language: en