Shortly after two UH-60 Black Hawk helicopters took off March 10 in Florida to perform training exercises with elite Special Operations Marines, things started going wrong. Thick sea fog hung just off the shore of the Florida Panhandle — so much so that one of the helicopters turned back. The second one continued on, and faced near blackout conditions.

“Gee, it’s dark as [expletive]. That don’t help none,” said one of the pilots moments before crossing the shoreline toward the Santa Rosa Sound, according to a transcript of their audio flight recording. A moment later, his fellow pilot added: “Yeah, it’s too dark to see the [expletive] water.”

What followed was an aviation accident that rocked both the Marine Corps and the Louisiana National Guard, which operated the aircraft. The UH-60 — call sign “MOJO 69” — crashed into the water southwest of Eglin Air Force Base at 8:21 p.m., killing all seven Marines and all four Louisiana Guardsmen on board.

A joint investigation by U.S. Special Operations Command and the Louisiana National Guard found that the cause of the accident was that both pilots of the doomed aircraft developed “spatial disorientation,” in which human senses lose track of where they are in space. Between 5 and 10 percent of all general aviation accidents can be attributed to it, and 90 percent of those are fatal, according to the Federal Aviation Administration.

The pilots — Chief Warrant Officer 4 George Wayne Griffin Jr., 37, and Chief Warrant Officer 4 George David Strother, 44 — likely struggled “after deciding to fly the mission in weather conditions that had lower ceilings and less visibility than they had been briefed as the minimum weather conditions authorized to conduct the mission,” according to the investigation’s report, first detailed Wednesday by The Irish Times.

“Shortly after going over the water, both CW4 Griffin and CW4 Strother exhibited signs of spatial disorientation,” said the report, a copy of which was obtained by The Washington Post.

“The flight data recorder and the cockpit communications transcripts indicate increasingly erratic flight control inputs and anxious verbal exchanges as both pilots tried, yet failed, to gain control of the aircraft,” it added. “Approximately two (2) minutes and five (5) seconds after going over water, MOJO 69 crashed into the water…There was an attempt to engage the autopilot, but the aircraft was outside the required flight parameters and the autopilot failed.”

The crash killed Griffin, Strother and the other members of their crew: Staff Sgt. Lance Bergeron, 40; and Staff Sgt. Thomas Florich, 26.

Also killed were: Marine Capt. Stanford H. Shaw III; Master Sgt. Thomas A. Saunders; Staff Sgt. Kerry M. Kemp; Staff Sgt. Andrew C. Seif; Staff Sgt. Liam A. Flynn; Staff Sgt. Marcus Bawol; and Staff Sgt. Trevor P. Blaylock. They were in Florida for amphibious training, and all part of the same tight-knit team with Marine Corps Forces Special Operations Command (MARSOC), according to Marines who knew them. Shaw, a Naval Academy graduate, served as their commander. Saunders was their team chief.

Griffin was the pilot in command on the mission, and at one point before the crash thought he was turning the Black Hawk to the east, when he actually sent it north, the investigation found. The helicopter rapidly climbed and descended and had erratic airspeed in its last moments, prompting Griffin to briefly relinquish control of the aircraft to Strother, and then try to work in tandem with him to prevent a crash.

The investigation found that the Marines did not pressure Griffin to call off the mission before takeoff, and had “high respect and over-confidence” in the air crew and the abilities of Griffin. The approximate cause of death was “impact with the water at an airspeed and angle that was not survivable.”

Maj. Gen. Joseph Osterman, MARSOC’s commander, said in a statement released to The Post on Wednesday that his organization worked closely with investigative teams, and called their work “thorough, complete and comprehensive.”

A senior officer from MARSOC provided a briefing to the primary next of kin for each of the Marines, and researched and answered subsequent questions they had.

“We continue to ensure that the families have all available information relative to the accident and that any additional support they need is provided,” Osterman said. “We are grateful for the tremendous support the families of our fallen have received since the accident occurred.”

Attempts to reach the Louisiana National Guard were not immediately successful.