The High Altitude Supplemental Oxygen (HASO) Working Group is a collaboration of business aviation professionals with an interest in addressing the challenges of complying with FAR 91.211. Specifically, the focus of this group is on hazards induced by the regulation while operating aircraft above an altitude of 41,000 feet.

The primary objective of the HASO Working Group is to provide a best practice recommendation to the Federal Aviation Administration for operations above 41,000 feet in aircraft certified to a ceiling of 51,000 feet. This group's recommendations will be based on risk analysis as it applies to a comprehensive evaluation of all exposure to hazards above 41,000 feet.

Members of the HASO Working Group consist of business aircraft pilots and operators, NBAA representatives, aircraft manufacturer representatives and aerospace physiology experts.