Aviation Experts Puzzled Over Events Leading To Greek Tragedy

Aviation experts in the US say they're puzzled over the crash of a Helios Airways 737-300 near Athens Sunday. Specifically, they're wondering how something less than a catastrophic depressurization incident could have incapacitated the flight crew, but apparently not everyone aboard the aircraft.

"It's odd," ALPA Executrive Air Safety Chairman Terry McVenes told the Associated Press. "It's a very rare event to even have a pressurization problem, and in general crews are very well trained to deal with it."

McVenes said, if the aircraft lost cabin pressure, then the flight crew didn't react according to that training. The aircraft didn't immediately descend to an altitude where pressurization wasn't required. It didn't make for the nearest airport -- but continued flying as a "renegade" aircraft for well over an hour.

When Greek F-16s intercepted the Helios 737, they were able to see inside the cockpit, where the copilot was slumped over the controls. The pilot was not visible to the fighter pilots. Oxygen masks were seen dangling from the cockpit ceiling.

Further, there were two people moving about in the cockpit, apparently trying to take control of the doomed 737. Although post-crash search teams reported finding bodies that were "frozen solid," at least 20 of the 121 people on board the flight were alive when it impacted the ground.

If there had been a sudden depressurization at 34,000 feet, the windows would have iced over, as was the case when Payne Stewart's Learjet crashed in 1999.

There were no obvious cabin breaches -- no holes in the aircraft visible to the F-16 pilots, no windows blown out. That appears to be a further indication that the depressurization wasn't sudden in nature and didn't kill all on board.

And yet...

"[The copilot] couldn't have been unconscious for a small decompression at 34,000 feet," Paul Czyz, professor emeritus of aerospace engineering at St. Louis University told the AP. "Something's amiss. Even if the pressurization system was failing, it doesn't fail instantaneously. Even if it goes fast, you can seal the cabin, you've got all the oxygen in the cabin to breathe, you've got the masks and you've got plenty of time to get to 12,000 feet."

Former NTSB Chairman Jim Hall told the wire service, "The accident did not have to occur. It has to be either a training issue or an equipment issue."

FMI: www.flyhelios.com