Tragic new details have emerged regarding the death of a Marine Corps F/A-18 Hornet pilot that was killed last year when his fighter collided with a KC-130J tanker off the coast of Japan. According to data retrieved from the downed pilot’s smartwatch, he survived adrift at sea for nearly ten hours, ultimately drowning only about an hour before he could have been rescued.

Capt. Jahmar Resilard, 28, was piloting a Marine Corps F/A-18 Hornet conducting mid-air refuelling operations from a KC-130J last December when the fighter collided with the refuelling aircraft. Six Marines died in the incident, including Resilard. According to reports, Resilard, who is referred to as “MP2” in the official investigation, was wearing a Garmin Fenix 3 smartwatch when he ejected from the fighter at 1:44 a.m. local time on December 6th. The watch continued to read a heart beat from the pilot for almost ten more hours before he ultimately drowned.

“The data from the watch indicated that MP2’s heart was beating at an average of 86 beats per minute until approximately 1130,” the report states.”MP2’s Garmin smartwatch indicates that MP2 was alive on the surface of the ocean from approximately 0145 until approximately 1130 (nine hours and 45 minutes) in 68-degree Fahrenheit water.”

Resilard’s body was recovered by members of Japan’s Maritime Self-Defense Force aboard the ship JS Setoyuki at 12:22 p.m — less than one hour after the Marine succumbed to the elements. A subsequent autopsy revealed a number of bumps and bruises as well as a head injury. The cause of death was ultimately ruled as drowning. Resilard was not wearing an anti-exposure suit, nor was his weapons officer who ejected and was recovered alive.

“He was an effective and dedicated leader who cared for his Marines and fellow fighter pilots with passion,” Lt. Col. James Compton, the squadron commander, said in a statement.

“His warm and charismatic nature bound us together and we will miss him terribly. We honor his service and his contribution to the Marine Corps and our great nation. Our thoughts and prayers are with his family and friends.”

Some have wondered if the suit could have helped Resilard survive longer in the 68-degree water, but the suits are considered optional and most pilots only wear them when absolutely necessary due to the added discomfort. None of the five Marines that died aboard the KC-130J were wearing anti-exposure suits either.

An investigation into the incident led to four officers from Marine All-Weather Fighter Attack Squadron 242 being relieved of duty, including the commander, executive officer, operations officer and aviation safety officer. Violations cited for their removal included the wrongful use of prescription and over-the-counter drugs by officers within the command, including by two that were involved in the crash. The investigation also called for increased search and rescue training alongside the host nation (in this case Japan), as well as for the U.S. to establish its own search-and-rescue capabilities at MCAS Iwakuni.