Direct cause of fatal Navy aircraft crash unidentified amid flight data absence

Firefighters work at the scene after a P-3CK maritime patrol aircraft crashed into a mountain in Pohang, North Gyeongsang Province, May 29. Newsis

The Navy on Thursday suggested multiple factors, such as insufficient training and the absence of an in-flight warning system, as potential factors behind a fatal maritime patrol aircraft accident earlier this year, but failed to identify a direct cause due to the lack of flight data.

The Navy released the outcome after its monthslong investigation into a P-3CK patrol plane that crashed on a mountain in Pohang, on May 29, six minutes after taking off for routine training from a nearby air base. No civilian casualties were reported, but all four crew members aboard were killed.

Surveillance camera footage had shown the aircraft flying on a seemingly normal operation and abruptly plummeting within a few seconds. The aircraft remained on a prearranged flight route, and the weather conditions in Pohang were favorable at the time of the accident, according to officials.

"In terms of mechanical factors, a probe into the aircraft's engine, propeller, fuel, steering and hydraulic systems showed they were all operating until ground collision," the Navy said in a release, following a probe conducted by a joint investigative committee comprising the military, civilian experts and the government.

"The direct cause of the accident was because the aircraft could not recover after a stall ... in a low altitude, low energy and steep angle of attack, steep roll situation," the Navy said, without providing further details on why the aircraft had stalled.

Details of the cause of the accident and the situation leading to it remained largely unaccounted for as both the flight data recorder and the cockpit voice recorder could not be recovered, prompting the committee to rely on wreckage of the aircraft, CCTV footage and aircraft simulator tests to determine possible causes.

The committee, however, said that "minor" internal object damage was found within one of the aircraft's four engines and while this did not affect the engine's operation, it could have possibly averted the pilot's attention due to the sound or vibration caused by it.

The committee ruled out the possibility of engineers failing to detect the internal object damage ahead of the flight, saying that the issue was not detected during regular maintenance.

Alongside the internal object damage, officials mentioned how the P-3CK was not fitted with equipment, such as an on-flight alarm system, designed to help pilots become aware of a stall.

Also among key factors that caused the accident was a lack of training meant to help pilots respond to stalls and other emergency situations in which the aircraft is uncontrollable.

"One of the most fundamental reasons was because training for recovering from a stall was not conducted," Cho Jong-kwon, head of the joint committee, told reporters. "There is high operational demand for the P-3 but there is not enough workforce, leading to insufficient opportunities for stall recovery training flights."

To prevent similar accidents, the Navy vowed to strengthen flight training for crew members while seeking an overall increase in workforce. The resumption of operating the grounded P-3CK patrol aircraft has yet to be decided.

The P-3CK aircraft that crashed in May was deployed to the Navy in 2010 and was set to retire in 2030. Initially manufactured by U.S. defense firm Lockheed Martin, it was supplied to the U.S. Navy in 1966.

Korea owns 15 P-3 aircraft, dubbed the "submarine killer" for its anti-submarine capabilities. The first eight of the 15 aircraft, labeled the P-3C, were deployed in 1995, and another seven, renovated by the defense firm Korea Aerospace Industries and named the P-3CK, were subsequently deployed.