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In Greece crash, new details but few answers

Investigators have learned the doomed Cypriot jet had a pressurization problem, but not why the pilots didn't react.

By BILL ADAIR and VALERIE PANOU
Published August 23, 2005

As Helios Airways Flight 522 was somewhere near Greece, with the co-pilot slumped over the controls and the captain missing from his seat, an urgent call came from the cockpit:

"Mayday! Mayday!"

That call probably came from a flight attendant who tried to maneuver the Boeing 737-300 jet, but the plane soon ran out of fuel and crashed, killing all 121 people on board.

New details about the crash released Monday by the Greek government and others familiar with the investigation shed light on the bizarre accident, but they also added to the mystery.

The plane failed to pressurize as it took off Aug. 14, but the pilots did not realize the problem. They spoke by radio with the airline's maintenance officials, but may have mistakenly believed they had a problem with their flap and slat settings, which configure the wings for takeoff. The warning horn for that takeoff setting is similar to the one for a pressurization problem.

The new details suggest that as the plane climbed, the pilots became disoriented by the lack of oxygen until they were incapacitated. But the revelations raise questions:

Why didn't the pilots realize they had a pressurization problem? In addition to the horn, there should have been other warnings.

Where was the captain? Why couldn't he be seen by the fighter pilots who were scrambled to intercept the plane after a long delay without radio communication?

How could the flight attendant survive so long at a high altitude? With the cabin depressurized and a limited supply of emergency oxygen, it's not clear how the flight attendant survived more than two hours to make the final radio call.

"It is one of the most baffling accidents I'm aware of in the last 20 years," said John Cox, a veteran accident investigator from St. Petersburg who flew 737s for 15 years. "There are many more questions than answers."

"It sneaks up on you'

At higher altitudes, people can't think straight.

The condition is called hypoxia, a lack of sufficient oxygen in the blood. It happens because there is not enough air pressure to push oxygen into the blood.

"The danger of hypoxia is that it is so insidious," said Rogers Shaw, a Federal Aviation Administration team leader who educates pilots about the condition. "It sneaks up on you, but by then, it's too late."

The condition is like being drunk. People may appear healthy, but they cannot respond to commands or questions. They don't realize they are in danger.

That might explain why the pilots didn't realize they had a problem. Even if the warning horn sounded at 10,000 feet as it was supposed to, they might have mistakenly believed they had the wing configuration problem. They may not have looked at the gauge on the cockpit ceiling that indicates the cabin pressure.

The information released Monday was from preliminary reports and could change as investigators complete their analysis. They are trying to determine why the plane did not pressurize after it took off from Larnaca, Cyprus, en route to Athens. They are likely to examine the switches that direct air from the engines into the cabin to make it pressurize.

In addition to the horn, the pilots should have received other warnings of a pressurization problem.

Once the plane reached 14,000 feet without being pressurized, the passenger oxygen masks should have automatically deployed. The pilots should have gotten a "master caution" light. That should have prompted them to check their other caution lights, which should have indicated the passenger masks were down.

"Wouldn't the flight attendants have called forward as soon as the masks dropped?" said Peter Goelz, former managing director of the National Transportation Safety Board. "It's hard to believe the pilots continued to ignore the warning signals."

The plane, on autopilot, kept climbing.

"Mayday!'

After the plane leveled at its cruise altitude of 34,000 feet, there was no contact with air traffic controllers. The pilots did not make the required call to Greek controllers as the 737 neared its destination.

Two F-16 fighter planes were dispatched to see what was wrong. The fighter pilots saw no one in the captain's seat and the co-pilot slumped over his controls.

With the plane at that high altitude for at least two hours, it's likely everyone aboard was unconscious. The emergency oxygen system provides only 12 minutes for passengers. Pilots and flight attendants may have had more, but not enough for the entire flight.

It also would be very cold. With the plane depressurized, there would be little heating to counter outside temperatures that were probably 40 degrees below zero.

But it's difficult to speculate about the effects on people at that altitude because little research has been done, said Shaw of the FAA.

The flight data recorder indicates the plane came out of a holding pattern, turned left, descended to 2,000 feet and then climbed to about 7,000 feet. The nature of those maneuvers indicate the plane was no longer being controlled by the autopilot.

Investigators believe 25-year-old flight attendant Andreas Prodromou was trying to save the plane. He cried "Mayday!" But the radio appears to have been set to the wrong frequency.

The plane ran out of a fuel and essentially became a giant glider. It crashed about 25 miles north of Athens.

--Information from the Associated Press was used in this report. Washington bureau chief Bill Adair can be reached at 202 463-0575 or adair@sptimes.com

[Last modified August 23, 2005, 02:45:30]