CLOVIS, N.M. (AP) — Air Force officials say a plane crash in which three airmen were killed earlier this year was caused by “human factors.”

The Eastern New Mexico News reports Capt. Kenneth Dalga, First Lt. Frederick Dellecker and Capt. Andrew Becker from the Cannon Air Force Base died when their plane crashed on March 14 while they were practicing approaches and landings near the Clovis Municipal Airport.

According to a report released last month by the U.S. Air Force Aircraft Accident Investigation Board, over control or under control of the aircraft caused the crash. The report does not indicate which airman was controlling the plane.

The report says the $18.3 aircraft did not have any mechanical malfunctions.