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Friday, February 24, 2006 - Page updated at 12:00 AM

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Alaska checking cabin pressure on entire fleet

Seattle Times aerospace reporter

Alaska Airlines is inspecting the pressurization systems on all 110 jets in its fleet following a recent flurry of in-flight mishaps.

The latest incident occurred Thursday afternoon aboard Flight 65, from Juneau to Anchorage, Alaska — just hours after the airline announced the planned inspections.

Alaska expects to complete its fleetwide checks in seven to 10 days. They are not expected to disrupt the carrier's flight schedule.

It was the airline's fifth incident in 10 days in which concerns about pressurization were raised. But Alaska said preliminary indications are there is no relationship between any of them.

And a National Transportation Safety Board official who studied Alaska's most dramatic recent depressurization incident said he did not consider the events especially troubling or unusual.

"Every morning, we get a list four pages long of these types of incidents," said Jim Struhsaker, a Seattle-based investigator with the NTSB. "Alaska does not have a corner on the market."

The NTSB keeps an eye out for patterns that might indicate underlying safety problems, but Struhsaker said he has not seen any sign of chronic woes in the Alaska pressurization incidents.

Recent incidents related to pressurization aboard Alaska Airlines flights


Feb. 23: Forty-five minutes after departing Juneau, Alaska, the altitude-warning horn sounded aboard Flight 65, indicating insufficient cabin pressure. The 737-400 descended to 10,000 feet and continued to Anchorage as planned. One passenger was treated for ear pain. The cause of the incident is under review.

Feb. 22: Flight 397 from Ontario, Calif., to Seattle landed in Los Angeles because the crew believed the MD-80 was pressurizing more slowly than usual. A post-flight inspection indicated the system was functioning within normal levels.

Feb. 21: Flight 100 from Portland to Denver returned to Portland after oxygen masks in the 737-400 deployed 15 minutes after takeoff. The reason for the deployment, and whether it was linked to a pressurization problem, are under review.

Feb. 18: Flight 1 from Washington Reagan National to Seattle was diverted to Washington Dulles after pilots noticed a problem with the 737-700's pressure six minutes after takeoff. Mechanics found a rear door had not been latched properly.

Feb. 14: Flight 578 from Seattle to Denver returned to Sea-Tac 15 or 20 minutes after departure after the 737-400's pressurization system malfunctioned. Five passengers were treated for ear and sinus pain. The cause was an electrical malfunction.

Dec. 26: Flight 536 from Seattle to Burbank, Calif., made an emergency landing at Sea-Tac after a 1-foot-by-6-inch hole opened in the fuselage of the MD-83 at 26,000 feet, causing the plane to lose pressure. A ramp worker had bumped the plane with a baggage loader before takeoff and failed to report it.

Source: Alaska Airlines

"Yes, they're having a little bit of a cycle," Struhsaker said, "but it just so happens they have been under the spotlight lately."

Yesterday's event occurred about 45 minutes after Flight 65 left Juneau.

Amanda Tobin, an Alaska Airlines spokeswoman, said the cabin altitude-warning horn sounded, signaling possible problems with cabin pressure.

The pressure was not low enough to cause oxygen masks to deploy, Tobin said.

Normal cabin pressure is roughly equal to what a person encounters at 8,000 feet above sea level.

The altitude-warning horn sounds if cabin pressure reaches the equivalent of 10,000 feet above sea level; oxygen masks deploy at the equivalent of 14,000 feet above sea level.

After the horn sounded aboard Flight 65, the pilots took the 737-400 down to 10,000 feet, and the flight continued to Anchorage.

Medics who greeted the plane referred one passenger for additional medical treatment for ear pain.

Between Feb. 14 and Feb. 22, four other Alaska flights were aborted shortly after takeoff because of pressurization concerns.

"Our initial investigations of each incident has found different root causes for each one, which would not indicate a systemic issue," Tobin said.

A spokesman for the Federal Aviation Administration could not be reached for comment.

Alaska's operations have been under a microscope since Dec. 26, when an MD-83 en route to Burbank, Calif., depressurized. A 1-foot-by-6-inch hole had ripped open in the plane's fuselage at 26,000 feet as the jet climbed away from Seattle-Tacoma International Airport.

The damage was caused by a ground worker for Menzies Aviation, an Alaska contractor.

Flight 536 made an emergency landing at Sea-Tac. No injuries were reported, but six passengers this month sued Alaska alleging they suffered "physical and emotional injuries" from the incident.

Struhsaker, the NTSB's lead investigator on that accident, said in an interview that he found no evidence of substandard training or oversight.

The NTSB will not publish his final report for another couple of months, but Struhsaker said yesterday his investigation is complete, and the findings should come as good news for Alaska and for Menzies, which handles Alaska's ramp operations at Sea-Tac.

Alaska hired Menzies in May to take over work previously done by 472 unionized workers the airline laid off in a cost-cutting move.

The worker who damaged the plane in December but failed to report it was a Menzies employee. Consequently, questions quickly arose about the quality and quantity of training Menzies workers were receiving.

"Whenever you have a big chunk of people coming in at once, it takes a while to get everyone on track," Struhsaker said.

He applauded the actions taken by Alaska and Menzies after the December incident. "They did a lot of things proactively to address the problem," he said.

Among this month's pressurization mishaps, the most significant was aboard Flight 578 from Seattle to Denver on Feb. 14.

The flight returned to Sea-Tac 15 or 20 minutes after takeoff after a cabin-pressure problem was detected. Five passengers were treated for ear and sinus pain.

Tobin said an electrical malfunction caused the incident, but she said Alaska investigators are trying to determine exactly what triggered it.

David Bowermaster: 206-464-2724 or dbowermaster@seattletimes.com

Copyright © 2006 The Seattle Times Company


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