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A Navy P-3CK patrol plane crashed on a mountain in Pohang, about 270 kilometres southeast of Seoul, on Thursday, killing all four Navy officers aboard.

The Navy said the joint investigation committee consisted of military authorities, including the Air Force and the Army, the Coast Guard and aircraft maintenance experts.

"To ensure the probe's transparency, reliability and fairness, the committee included not only officers from other armed forces but also civilian experts," a Navy official said.

Surveillance camera footage, provided by the Navy, showed the aircraft flying on a seemingly normal operation and abruptly plummeting within a few seconds, Yonhap news agency reported.

Navy officials suspected a mechanical problem in the aircraft as the possible cause for the crash, but also did not rule out any other possible causes, including a bird strike or a sudden change in the weather.

Earlier on May 30, crew members aboard a maritime patrol aircraft that fatally crashed had no communication with the ground control tower over an emergency situation until the last minute.

"The last communication between the control tower and the aircraft occurred at 1:48 p.m., and there were no details indicating an emergency situation," the Navy said.

The aircraft was usually based on the southern island of Jeju but had flown to Pohang for touch-and-go training due to heavy civilian air traffic at the Jeju airport.

The accident occurred when the aircraft was circling to the right after completing its first round of training, according to the Navy. The aircraft remained on a prearranged flight route, and the weather conditions in Pohang were favourable at the time of the accident, officials said.

The 86-second video, comprising two clips filmed in separate locations, showed the aircraft suddenly nosediving into an area near a block of residential homes while flying on a circular route.

The armed service plans to determine the cause of the accident by comprehensively analysing the aircraft's track data, sound clips recorded on a cockpit voice recorder retrieved earlier in the day and debris of the aircraft.

South Korea operates 16 P-3 aircraft, dubbed the "submarine killer" for its anti-submarine capabilities. The first eight of the 16 aircraft, labelled the P-3C, were deployed in 1995, and another eight, renovated by the Defence firm Korea Aerospace Industries Ltd. and named the P-3CK, were subsequently deployed.

- IANS