Accident Boeing C-17A Globemaster III 10-0215, Monday 21 August 2023

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Date:	Monday 21 August 2023
Time:	08:06
Type:	Boeing C-17A Globemaster III
Owner/operator:	USAF
Registration:	10-0215
MSN:	50244/F243
Fatalities:	Fatalities: 0 / Occupants:
Other fatalities:	0
Aircraft damage:	None
Category:	Accident
Location:	off the Alaskan coast - United States of America
Phase:	En route
Nature:	Military
Departure airport:	Anchorage-Elmendorf AFB, AK (EDF/PAED)
Destination airport:	Anchorage-Elmendorf AFB, AK (EDF/PAED)
Investigating agency:	USAF AIB

Narrative:
A General Schedule civilian (MM) assigned to the Missile Defense Agency (MDA), Redstone Arsenal, Alabama, suffered cardiac arrest and passed away while under treatment for decompression sickness (DCS)-related symptoms at the Joint Base Elmendorf-Richardson (JBER), Alaska, Emergency Room (ER).
On the previous day, 21 August 2023, the civilian participated in a high-altitude simulated airdrop mission on the C-17 from the 437th Airlift Wing, Joint Base Charleston, South Carolina. The aircraft departed JBER at 1008L on a planned seven-hour mission to test ranges off the Alaskan coast. Following uneventful takeoff, departure, and cruise portions of the flight, at approximately 1400L and with the aircraft fully depressurized to 24,900 feet mean sea level (MSL) and all personnel on oxygen, the Mishap Crew (MC) opened the cargo doors and executed the test pass of the medium range ballistic missile payload. Upon test completion and shortly following cargo door closure, the civilian signaled distress to nearby mission essential personnel (MEP). He was sweating profusely, complaining of shortness of breath and pain in his right arm, was attended to by High Altitude Airdrop Mission Support (HAAMS) physiological technicians. Following the aircraft’s arrival at 1700L, JBER Emergency Medical Services (EMS) transported him via ambulance
to the JBER ER at 1749L.
Upon hospital arrival the attending physicians immediately began treating the MM for DCS and coordinating follow on treatment in a hyperbaric chamber. At 0806L the following day, 22 August 2023, as the MM was being transported to higher care at a local hospital, he entered cardiac arrest. ER personnel were unable to resuscitate the MM and he was pronounced deceased at 0832L on 22 August 2023.
The Medical Examiner (ME) determined the cause of death as decompression sickness with contributing factors of obesity, hypertension, and atherosclerotic cardiovascular disease, with an unknown role for SARS-CoV-2 infection. The manner of death was declared as accidental.

The Accident Investigation Board (AIB) President found, by the preponderance of the evidence, that this mishap was the result of decompression sickness induced by the high altitude, unpressurized portion of the military test mission. The AIB President found, by the preponderance of the evidence, the following factor substantially contributed to the mishap: the pre-existing and underlying medical conditions of the MM.

Accident investigation: