Air force spokesman Air Commodore Sarfraz Ahmed Khan said the weather and aircraft were fit for flying and there was no sabotage.

A Pakistan air force Fokker F-27 carrying Air Chief Marshal Mushaf Ali, 55, his wife and 15 others went down in mountains near Kohat about 175 kilometers (108 miles) northwest of here on February 20.

All on board, including several senior air force officers, were killed.

"A fatal mistake by the pilot caused the accident," Khan, releasing the report of a high level board of inquiry, told a news conference.

"The board carried out an in-depth investigation into all the possible causes, which included sabotage through the use of any internal or external device or in any manner, technical fault, bird hit, foreign object damage, inflight fire."

Witnesses had described heavy clouds at the time of the crash and said the plane appeared to be in trouble before it came down in the Tolanj Jadid hills as it was preparing to land at the Kohat air base.

The findings said in the final stage of flight the pilot was passing through clouds without having visual contact with ground.

"The pilot descended earlier than the scheduled time," attempting to maintain contact with the ground.

"As a consequence of this crucial pilot error, the aircraft hit a ridge, which was 3,000 feet above sea level and completely hidden under the clouds," Khan said.

The early deccent of the pilot was against the standard operating procedures, he added.

The tragedy was the worst in the country's history since the 1988 plane crash that killed former president General Mohammad Zia ul Haq and several senior military officers.

WAR.WIRE