Major Harry Schmidt and Major William Umbach each face charges of manslaughter, assault and dereliction of duty after dropping a 500lb (225 kg) bomb on a Canadian military unit in April 2002.
The bombing near the southern city of Kandahar is one of a series of embarrassing "friendly fire" incidents in Afghanistan since US forces went in more than a year ago.
Lawyers for the two men said that the pilots were not told that Canadian troops were in the area, and thought their F-16s were coming attack.
"There are two American patriots who are well-trained, who, based on that, believed they were under attack. And there is no way that there should be a criminal prosecution for an honest mistake," said Major Umbach's lawyer, David Beck.
No fire
"The Air Force has a problem. They have administered 'go pills' to soldiers that the manufacturers have stated affect performance and judgment," said Mr Beck.
However, the Air Force had said that service personnel use the pills on a voluntary basis, and that their effects have been tested.
The court heard evidence from a Canadian infantry Captain Joseph Jasper.
He said that there had been "quite a bit of anti-tank fire" during training exercises, but he said no weapons had been fired in the few minutes before the American bombs fell.
"Basically we looked at each other and said: 'What the hell was that?'" said Captain Jasper.
This is first time manslaughter charges have been brought against pilots of any branch of the US service for job performance in a war situation.
If sent for court-martial and convicted, the men could be sentenced to up to 64 years in a military jail.
Canadian criticism
The "Article 32" hearing - at the Barksdale Air Force base in Louisiana - is expected to last up to three weeks and include witnesses and videotape evidence.
The public is barred from the proceedings, which will be conducted by air force officials, but are similar to a civilian grand jury hearing.
The incident drew sharp criticism from Canada, and a joint US-Canadian inquiry in June 2002 blamed the pilots for the deaths of the four Canadian soldiers.
Eight other Canadian personnel were injured when the F-16 pilots dropped a laser-guided missile on night-time live-ammunition exercises, thinking they were hostile fire from Taleban or al-Qaeda forces.
One of the expected witnesses is the pilots' commander, Colonel David Nichols, who - months beforehand - complained to his superiors about communications problems that in his view were bound to eventually lead to deaths in "friendly fire" incidents.
Another issue that lawyers intend to raise is that charges have not been filed in other similar incidents, for example when US helicopters attacked an Afghan wedding celebration in July 2002 killing 40 people. |
