Prevention of decompression sickness in current and future fighter aircraft.

United States Air Force oxygen regulators set to "NORMAL OXYGEN" deliver up to 60% nitrogen to the pilot at cockpit altitudes of 15,000 to 20,000 ft (4573-6096 m). Research chamber exposure to these altitudes while breathing 50% nitrogen has resulted in high grades of venous gas emboli. Expansion of existing gas emboli following an unplanned decompression to ambient aircraft altitude (e.g., loss of canopy) could result in rapid development of decompression sickness (DCS) symptoms. To reduce this potential problem, regulators in current fighters should be set to "100% OXYGEN" until descent from cruise to increase denitrogenation. The United States' Advanced Tactical Fighter and the European Fighter Aircraft may be designed to cruise above 50,000 ft (15,240 m), where cockpit altitudes exceed 20,000 ft with a 5-psi differential (psid) cockpit pressurization schedule. Increasing cockpit differential pressure to 7 psid while breathing 100% oxygen would greatly reduce the chance of significant emboli formation and the potential for DCS, but would slightly elevate the risks associated with pulmonary overpressure during rapid decompression.