Mitigation of Decompression Sickness in U-2 Operations

Background: Decompression sickness (DCS) is a common hazard in the U-2 high altitude reconnaissance aircraft. For those pilots who appear to be more susceptible to DCS, several procedures could reduce the mission impact including: increased ground level or in-flight denitrogenation, suit pressure applied early in the mission, or inclusion of a 10-min period of strenuous, upper- and lower-body exercise at the beginning of a 60-min prebreathe. Methods: A procedure referred to as Exercise During Pre-breathe (EDP) provided significantly better protection from DCS than an equal period of resting pre-oxygenation for most subjects tested. Results: The use of EDP was introduced to all sorties in the U-2 program beginning in April 2010. Conclusion: This report documents the background, actions, results, and recommendations relating to enhancement of pre-oxygenation with exercise for pilots who require additional protection from the symptoms of DCS.