Photos show that a shot fired from a US Airways pilot's pistol blasted a small hole through the cockpit wall of a plane that left Denver and landed in North Carolina.
The photos obtained Tuesday by The Associated Press show a small entry hole in the lower side of the cockpit wall and a small exit hole on the exterior below the cockpit window.
The AP described the photos and the bullet hole in the Airbus A319 to US Airways spokesman Phil Gee, who said "they sound authentic."
Airline officials have said the "accidental discharge" Saturday aboard Flight 1536 from Denver to Charlotte did not endanger those on board. There were 124 passengers, two pilots and three flight attendants on the flight at the time. No one was injured.
Authorities said the passengers didn't even know that the gun was discharged while the plane was at about 8,000 feet in the air and on approach to the Charlotte airport.
A federal aviation security source told ABC the discharged round hit the side of the Airbus A319 and did not hit any sensitive equipment. The round pierced the cockpit wall but did not result in depressurization.
Air safety experts said the hole could have caused the plane to rapidly depressurize had it been in a window at a higher altitude.
"There are two issues: would they (the crew) have enough oxygen to remain alert," said Earl Dowell, an aeronautical engineering professor at Duke University. "If the crew could no longer control the airplane, that would be a big deal. And the rapid loss of pressure might damage the structure itself."
But both Dowell and Fu-Kuo Chang, a professor of aeronautical engineering at Stanford University, said that airplane design emphasizes safety and that such a blast -- even if it knocked out a window in mid-flight, isn't likely to cause the kind of damage that would lead immediately to a crash.
"If not repaired, it may cause a problem. It could get bigger. For a single bullet, it would not be a factor for the safety of the airplane," Chang said. "If it hit the window, it may be a problem for depressurization. I still don't think it would cause a crash."
Dowell pointed to a 1988 Aloha Airlines flight in Hawaii in which the roof of the jet ripped off after an explosive decompression at 24,000 feet. A flight attendant was blown out of the plane, but the passengers -- many of whom were injured -- remained strapped in their seats, and the pilot safely landed the aircraft.
"If they lost a window, the people near that window would have been substantially uncomfortable," Dowell said. "You probably wouldn't have crashed the airplane. But there could have been some frightened people."
Gee said the pilot has been taken off duty during the investigation by the Transportation Security Administration.
Pilot Part Of Flight Deck Officer Program
The gunshot marked the first time a pilot's weapon has been fired on a plane since the Flight Deck Officer program was created following the Sept. 11, 2001, terrorist attacks. The program allows pilots and navigators to use a firearm to defend against any act of air piracy or criminal violence.
"The pilot was authorized to be in possession of the weapon and he completed the appropriate training," the TSA said.
The pilot in question, who was sitting in the left seat, last re-qualified on Nov. 7, 2007.
An aviation expert said the only way he can surmise a gun going off in flight is if it was not properly stored.
"A properly stored weapon with the safety on does not go off," said aviation expert Michael Boyd. "The gun had to be out in the open. The gun had to be handled. The gun had to be in somebody's control."
All Federal Flight Deck Officers use Heckler and Koch universal self-loading 40-caliber pistols and are allowed to carry these weapons ready to use -- like any other law enforcement officer.
"This is an extremely safe and reliable weapon," said Greg Alter of the Federal Air Marshal Service. "It's not going to discharge on its own, is the bottom line."
Alter said the high-priced and high-quality H&K USP was specially selected for the program.
Gun safety expert Ronald Scott, a ballistics expert who served for 25 years with the Massachusetts State Police, said the gun wouldn't discharge accidentally if dropped or jarred in some way.
"It's a top-of-the-line model," Scott said. "They're accurate and highly reliable. This is not something that you would just walk into a gun store and buy. And it's also not something that goes off by itself. ... Someone would have to squeeze the trigger."
The Federal Flight Deck Officers need to be re-qualified twice a year. Pilots must volunteer, take a psychological test and complete a weeklong firearms training program run by the government to keep a gun in the cockpit.
Pilots in the program undergo 50 hours of training at the federal Law Enforcement Training Center in Artesia, N.M.
Alter said it appears the pilot of the US Airways flight wasn't following "proper procedures. ... We just don't know exactly what procedure wasn't being followed."
Since April 2003, about 5,000 flight deck officers -- captains or first officers -- have gone through the training program and received permission to carry weapons in the cockpit, said Capt. Bob Hesselbein, chairman of the Air Line Pilots Association's National Security Committee. The union represents more than 61,000 pilots at 43 airlines.
Gee declined to say how many US Airways pilots have graduated from the program and carry guns while on duty, citing security concerns.
The TSA initially opposed the Flight Deck Officer program to arm and train cockpit personnel. Agency officials worried that introducing a weapon to commercial flights was dangerous and that other security improvements made it unnecessary. Congress and pilots backed the program.
The jet will be grounded at Charlotte-Douglas International Airport for several more days as repairs are made. The Federal Aviation Administration said Tuesday it won't be involved in looking at why the gun went off but will investigate to make sure the plane is safe before it returns to service.
"We want to make sure there was no structural damage and no systems on board were damaged by the bullet," said FAA spokesman Ian Gregor said. "We want to take a look at the aircraft to make sure it's in an air-worthy condition."
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