The crew of an Air Force AC-130 gunship that mistakenly fired on friendly forces in Afghanistan last March, killing an American soldier, was plagued by equipment problems including flawed navigation systems, a Central Command investigation summary says.

The brief summary confirmed what was widely reported last month — that Chief Warrant Officer Stanley L. Harriman was killed by gunfire from the AC-130, not by enemy mortar fire as U.S. authorities originally said.

The matter has been under investigation since March 29.

The summary was released late last week by Central Command, which runs military operg under attack on March 2 as U.S. and Afghan allied forces were beginning a major offensive, called Operation Anaconda, against Al Qaeda and Taliban fighters.

The AC-130, a special operations aircraft armed with side-mounted 40mm and 105mm cannons, had been assigned to provide armed escort and reconnaissance for a ground convoy — a typical mission for the aircraft.

The aircraft broke away from the convoy to respond to calls for armed support from other ground units, the investigation report said. While away, an element of the convoy, led by Harriman, separated from the main group.

When the AC-130 returned, its crew mistakenly identified Harriman's convoy as an enemy force. The crew opened fire after requesting and receiving permission, killing Harriman and wounding three U.S. and 14 Afghan soldiers.

The investigation summary says the AC-130 had experienced equipment problems throughout the mission, including "continuous problems with their navigation systems."

Conscious of the navigation system breakdowns, the crew found its way by visual observation of ground reference points. However, the crew had misidentified the ground reference points by which it was navigating when it encountered Harriman's convoy.

"The 'enemy forces' were actually the convoy element led by Chief Warrant Officer Harriman," the report said.

The report provided no details on the nature of the problem with the AC-130's equipment problems, including its navigation system.

The AC-130, known as the Spectre, has a combat history dating back to the Vietnam War. It played a large role in the early months of the war in Afghanistan. Before releasing the report on the March 2 mistaken attack, Central Command had not indicated any navigation or other equipment problems with the AC-130.

An Air Force fact sheet says the AC-130 is equipped with sophisticated sensor and navigation systems that allow it to unleash "surgical firepower" at night and in advance weather. It says the sensors are designed to enable the crew to visually or electronically identify friendly ground forces and targets "any place, any time." They include a television sensor an infrared sensor and radar.

Central Command did not release the full investigation report, which is classified because of sensitive information about the AC-130.

Harriman, 34, a native of Nixa, Mo., and a member of the Army's Special Forces, was the first of eight Americans killed in Operation Anaconda. The seven others were killed when two U.S. helicopters took enemy fire from Al Qaeda defenders.