Accidents
Known Oxygen System Deficiency Preceded Fatal Crash
Air Force intercept confirmed no cockpit or cabin activity before crash
 Overview of ADS-B flight track, flight plan waypoints, and accident location, with selected time and altitude labels.
Overview of ADS-B flight track, flight plan waypoints, and accident location, with selected time and altitude labels. © NTSB

A Cessna Citation 560 that flew unresponsive for nearly two hours before crashing into mountainous terrain in Virginia on June 4, 2023, had known unresolved deficiencies in its oxygen system, according to the NTSB’s final report. Although it could not be verified from medical evidence, investigators concluded that the pilot and passengers were likely incapacitated by hypoxia following a loss of cabin pressurization; the report also noted a lack of supplemental oxygen onboard.

Two days before the flight, maintenance reports documented that “the pilot-side oxygen mask was not installed, and the supplementary oxygen was at its minimum serviceable level. No evidence was found to indicate that the oxygen system was serviced or that the pilot-side oxygen mask was reinstalled before the accident flight.”