As was reported in multiple news outlets on February 5th, 2022, a trainee in Basic Underwater Demolition/SEAL (BUD/S) training recently died shortly after completing the rigorous 5-day period of First Phase training known as Hell Week. Per news reports, the trainee was hospitalized a short time — possibly 2 hours — after Hell Week ended, along with a second trainee who was still being treated as of the writing of this article. The trainee who perished was identified as 24-year-old U.S. Navy Seaman Kyle Mullen, from New Jersey.
In addition, U.S. Army Special Forces training has also reportedly suffered two fatalities recently, although no details have yet been publicly released, and those fatalities, as well as their causes, cannot be confirmed by this author.
The U.S. Navy has not yet released any details on the cause of Seaman Mullen’s death, and this article will not attempt to guess at what caused the tragic incident. However, we can point to some of the various causes of non-trauma death of Special Operations candidates and personnel that have occurred during training evolutions. While it is publicly unknown what led to the death of the most recent fatality at BUD/S, the statistics point to one of the below as the most likely medical cause.
Data on previous fatalities in Special Operations Forces (SOF) training are hard to come by, beyond press accounts, and for this article, the author spoke with a former U.S. Special Operations Command surgeon with first and second-hand knowledge of incidences of fatalities in SOF training.
1. Hypoxic Loss of Consciousness (HLOC)
HLOC occurs when a person performs some sort of breath-hold evolution, usually underwater, which then leads to a loss of consciousness and subsequent death by drowning. Obviously, Seaman Mullen was not performing any breath-holding evolution after Hell Week had ended. BUD/S trainees and instructors have succumbed to this in the past, during underwater knot-tying evolutions, dive tower ascent training, and when simply practicing breath-holding in a pool or in the open water.
2. Swimming-induced pulmonary edema (SIPE)
SIPE is a respiratory condition that typically occurs during physical exertion — like swimming — while a person is submerged in water. Fluids from the blood leak from the small blood vessels of the lung and into the alveoli. There has been speculation that cold water exacerbates this problem, although that has not been scientifically proven. According to one former diving medical officer in the Naval Special Warfare (NSW) community, SIPE would not be considered a likely cause of death for a trainee several hours after Hell Week had secured, unless there was a significant length of immersion in the water just beforehand. Triathletes also sometimes suffer from SIPE, although incidences of death from SIPE appear to be rare.
Incidences of SIPE are fairly common in BUD/S training, and a recent 2019 study found a 5% instance of SIPE in a study of 2,117 BUD/S trainees over 15 months. That is 106 cases in total amongst that studied group, none of which were fatal in that particular study. Data on death from SIPE in SOF training is difficult to come by, but at least one death in the 1990s at BUD/S is suspected of being due to the illness.
A significant drop in body temperature, hypothermia can result in death if not recognized and treated adequately. BUD/S has suffered training deaths due to hypothermia (a Second Phase trainee died following the 5.5 nautical mile open water swim), as has Ranger training, and Special Forces training. Hypothermia is a persistent and constant threat in Special Operations training. Instructors in BUD/S, in particular, are trained to recognize its signs early, and to take the necessary precautions before a student gets progressively worse. BUD/S students spend a large portion of training in a state of mild hypothermia.
A significant rise in body temperature, heatstroke (severe hyperthermia) is the most significant and dangerous phase of heat-related illness. It leads to multi-organ failure and death if not recognized and treated. It has also claimed the lives of multiple trainees across multiple services. In 2014, for example, four British Special Air Service (SAS) trainees died as a result of hyperthermia while in training.
Drowning is a real and persistent danger in SOF training, especially BUD/S, as well as any Special Operations training that involves significantly hazardous evolutions in the water. Special Operations trainees and already-qualified personnel have drowned in both pools and open water, and even in inland waterways in a war zone. Drowning, in this case, is differentiated from an HLOC death, as in these cases, trainees were not attempting to hold their breath when they drowned.
Other non-trauma dangers
While the above medical causes of death in Special Operations training are the most common non-trauma deaths, other causes — such as trauma and viral or bacterial infection — can also explain some training fatalities. Parachuting, fast roping, boat insertion through the surf zone, live-fire exercises, and helicopter operations have all caused deaths in training operations in the past.
As far as infections, pneumonia is very common at BUD/S, though this author cannot find any verified cases of it causing a fatality. Necrotizing fasciitis has also occurred at BUD/S on multiple occasions, although it was again unclear if it had caused any fatalities in BUD/S trainees. A fast-spreading and potentially deadly bacterial infection, necrotizing fasciitis can be especially insidious in individuals with compromised immune systems, like BUD/S trainees.
Regardless of what caused Seaman Mullen to suffer his fatal medical emergency in the hours immediately following the end of Hell Week, it is heartbreaking that yet another trainee has died in the course of attempting to make it through the training. May he rest in peace.
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Feature image: U.S. Navy photo by Petty Officer 1st Class Abe McNatt