When I was on active flight status for the Navy, we were required to renew our aviation physiology (AvPhys) training every four years, minimum, which included, parachute system/ejection seat training, altitude chamber, helo dunker, etc.
During one training session at the older Naval AvPhys Facility we traveled to (before the Navy built a new state-of-the art facility at our Home Plate), one of my colleagues was renewing and had just gotten out of swim and survival float pool, which is performed in full flight gear, including flight suit, helmet, steel-toed flight boots, g-suit, gloves, etc. After the instructors/safety divers had also exited the pool and were preparing to move his group next door for the next phase of their training, my colleague pointed to the bottom of the pool, saying, "Hey, what about that guy?" The team of instructors all looked where he was pointing to see another aviator laying face-down motionless on the bottom of the pool and obviously not breathing!
Uttering some harsh expletives, two of the "safety divers" frantically dove into the pool, pulled the aviator to the surface, were they and others were thankfully able to revive him!
As the story unfolded, we learned he was a U.S. Marine Captain (O-3) MH-53 aviator from an east coast USMC Air Base. Thankfully he lived, but because he'd lost consciousness for a period of time, that poor man was grounded for an entire year, all because the safety team fucked up and nearly got one of their charges killed!
I'm quite certain he was happy to be alive, but I'm also quite sure he put some very choice words in his Christmas Cards to the Navy for the rest of his aviation career! I never knew what happened to those AvPhys staff members, but I wouldn't be surprised if one or more were taken to Captain's Mast or worse!
By the way, the Marines admit they are part of the "Department of Navy" . . . but they claim it's "The Men's Department!"