A CH-53E Super Stallion helicopter lands on the flight deck of the amphibious assault ship USS Peleliu

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2 CH-53 helicopters crashed during night training mission

"Low aircraft readiness" hurt pilot proficiency, Marines say

CNN  — 

The crash of two US Marine Corps helicopters that killed 12 troops off Hawaii in January was caused by pilot error, according to a report from military investigators.

The CH-53E helicopters collided during a night training exercise off the main Hawaiian island of Oahu on January 14. Both copters plunged into the Pacific Ocean and all aboard died.

“The investigation determined that the aircraft failed to maintain adequate distance during the flight and the aircraft collided,” said a statement from Lt. Col. Curtis L. Hill, US Marine Corps Forces Pacific spokesman.

“Investigators believe that the low light conditions made it difficult for the aircrew to recognize the rapid decrease in separation between the aircraft which led to the collision,” Hill said.

Along with pilot error, contributing to the crash were “low aircraft readiness leading to inadequate pilot proficiency, human factors and the squadron’s lack of focus on basic aviation practices,” the statement added, noting that both aircraft were mechanically sound.

According to the Investigative Reporting Program at the University of California, Berkeley, which gained access to the official report on the crash, the rear copter in the two-aircraft formation fell behind the forward one as they were flying over the ocean at an altitude of 1,500 feet.

The rear copter accelerated to catch up just as the first made a left-hand turn across its path, resulting in the collision, the IRP said.

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12 Marines go missing after 'routine' training mission
00:53 - Source: KGMB KHNL

The IRP reported that the four pilots involved in the accident had not flown enough hours in the month preceding the crash to be considered proficient in the operation of their aircraft. Two of the Marine pilots also had little time flying with night-vision goggles in the months leading up to the crash, IRP said.

The IRP report was first posted online this week by Civil Beat and HuffPost Hawaii.

The aircraft were from Marine Heavy Helicopter Squadron 463 based at Marine Corps Air Station Kaneohe Bay.

CNN’s Artemis Moshtaghian contributed to this report.