The two U.S. pilots who mistakenly killed four Canadian soldiers in Afghanistan last year showed a "reckless disregard" for standing orders by attacking instead of continuing on their way, an Air Force general testified Tuesday.

Brig. Gen. Stephen Sargeant, who headed the investigation into the bombing, said the pilots failed to follow procedure by not communicating about gunfire they had spotted on the ground. At an altitude of more than 15,000 feet, the pilots were not in range of the gunfire, he said.

"At that point it would have been possible to continue on," Sargeant said at a military hearing to determine whether the pilots will face a court-martial for the deadly bombing last April.

Defense lawyers asked the hearing officer, Col. Patrick Rosenow, to throw out Sargeant's testimony. They said the law bars the opinion of investigators on the cause of the accident from being considered as evidence in civil military proceedings.

Rosenow heard arguments on the issue, but did not immediately rule and allowed Sargeant to keep testifying. He said he would disregard the testimony if he ruled in favor of the defense.

Maj. Harry Schmidt, who dropped the bomb, and Maj. William Umbach, who was flying another F-16 and was mission commander, were charged with involuntary manslaughter and other counts after investigators concluded they had acted rashly by attacking ground fire rather than evading it. The ground fire came from live-ammunition exercises by the Canadian troops.

Defense lawyers have said the pilots were unaware allied troops were in the area, in part because of poor military communication, and fired in self-defense. The defense has also suggested the pilots were pressured to take Air Force-issued amphetamines that impaired their judgment.

Earlier in the hearing, experienced F-16 pilots suggested the pilots were justified in attacking if they believed it was necessary to do so in self defense. Prosecutors brought that up with Sargeant.

"Did you find this to be a rapidly unfolding situation?" Col. John Odom Jr. asked.

"No, in that there was nothing in the tapes that showed me a sense of urgency to force this situation rapidly drawing to the conclusion it did," Sargeant replied.

According to Sargeant, the airmen should have reported the ground fire to flight controllers and stayed on their course.

Schmidt then violated standing orders to keep himself out of danger by slowing his F-16 from about 500 mph to 400 mph and dropping his altitude to just over 10,000 feet, the general said. A pilot who thought he was under surface-to-air fire should have known the changes would put him in danger.

"He could have just left," Sargeant said. "He should have accelerated out of this."

Instead, Schmidt dropped a 500-pound, laser-guided bomb on the Tarnak Farms firing range near Kandahar. Eight Canadians were wounded in addition to the fatalities, the nation's first in combat since the Korean War.

Sergeant also said Umbach was at fault for letting Schmidt take control of the mission. As lead pilot, Umbach failed to immediately order Schmidt to evade after Schmidt spotted the ground fire, the general said.

Umbach "did not live up to his part of the contract as a flight lead," Sargeant said.

Defense lawyers attacked Sargeant's testimony as self-serving and possibly illegal because he had brought the charges against the pilots.

"He said nothing that he has not already said," Umbach's lawyer, David Beck, said after Tuesday's hearing. They called Sargeant a surprise witness and one they had tried to call to discuss possible bias by investigators only to be told he would be unavailable.

If convicted on all charges, which include aggravated assault and dereliction of duty, Schmidt and Umbach face up to 64 years in prison.