IWAKUNI, Japan -- Inadequate training, poor leadership and a lack of pilot proficiency are to blame for a deadly collision between a United States Marine Corps fighter jet and tanker aircraft off Japan, the Marines said this week.
The December 6 accident left six aviators dead and almost a $150 million of aircraft at the bottom of the Pacific.
As a result of the investigation, four officers from Marine All-Weather Fighter Attack Squadron 242, based in Iwakuni, Japan, were relieved of their duties, according to a Marine Corps statement.
The Corps must be more vigilant in ensuring that safety procedures are followed and risks evaluated, the statement said.
"We must all learn from these failures and not repeat them," said Lt. Gen. H. Stacy Clardy, commander of the III Marine Expeditionary Force, to which the units involved belonged.
The accident occurred as two Marine F/A-18D fighter jets and a KC-130J tanker aircraft were conducting aerial refueling over the Pacific in the early hours of December 6.
After both fighter jets took fuel from the tanker plane, the second plane to complete the procedure tried to move away from the tanker using "a non-standard maneuver for air-to-air refueling," according to the Marine Corps statement.
The maneuver had been approved by mission controllers, it said.
"The pilot of the second F/A-18D was not experienced in conducting nighttime air-to-air refueling operations," the statement continued. "The investigation indicates the mishap pilot lost situational awareness, unintentionally crossed over the top of the KC-130J from left to right, and collided with the rear of the tanker."
Both aircraft plunged into the Pacific.
All five of the Marines aboard the tanker, Lt. Col. Kevin Herrmann, Maj. James Brophy, Staff Sgt. Maximo Flores, Cpl. Daniel Baker, and Cpl. William Ross, were killed.
The pilot of the F/A-18, Capt. Jahmar Resilard, was rescued after the crash but later died of his injuries. The weapons officer aboard Resilard's jet was the only survivor of the accident.
"The loss of these Marines is still felt within their squadrons, their communities, and across the Marine Corps," the statement said.
While the statement said four officers had been relieved of their duties, it noted that review of the accident continues and further disciplinary action is possible.
After the crash, US, Japanese and Australian forces conducted more than 800 hours of air and maritime search operations, covering more than 35,000 square miles of ocean, in an attempt to find survivors, US Forces Japan said in December.
In a salvage operation from May 27 to June 7 of this year, human remains along with the cockpit voice recorder and flight data recorder of the KC-130 tanker were recovered from the ocean floor, the Corps said.