Alaska Airlines is inspecting the cabin-pressure system on every plane in its fleet after problems on five flights in three days this week caused the jets to be diverted or to descend to a lower altitude, the company said Friday.
Similar incidents occurred Feb. 14 and Feb. 18. The airline said each of the seven incidents, most of them clearly related to pressurization, involved a different jet.
No common cause for the incidents has been found so far, Alaska Airlines spokeswoman Amanda Tobin said. Alaska has 110 planes, she said.
Several people apparently suffered ear or sinus injuries on two flights. On one of them, Flight 65 from Juneau to Anchorage on Thursday afternoon, the plane was met at Ted Stevens Anchorage International Airport by paramedics, who escorted two passengers to a hospital, airport authorities said.
That flight was routine until about 45 minutes after takeoff from Juneau when the cabin altitude warning horn sounded, an indication that air pressure within the passenger compartment had fallen to the equivalent of 10,000 feet above sea level or higher, Tobin said.
Rep. Carl Gatto of Palmer was sitting in the seventh row at the window. The plane was cruising at 38,000 feet, and the attendants were passing out snacks, when "there was this pretty good vibration," he said.
"The (jet's) power was kept real back, and the nose was pitched downward," said Gatto, who is a pilot. "He was simply trying to lose altitude fast, and it was fast, and not only that, my ears started popping fast."
The pilot had reported an emergency to air traffic controllers and told them he would land the plane in Yakutat, according to Joette Storm, a spokeswoman in the Anchorage office of the Federal Aviation Administration.
"I was staring out the window and I was thinking, 'If we keep this up, we're going to land in the snow," Gatto said. "We have to arrest the rate of descent, because we're too far from Juneau and we're not close enough to Yakutat."
Gatto, who had a head cold, had to work to keep his ears clear, he said.
"The vibration and noise were deafening," said Mary Ann Pease of Anchorage, who was sitting in the third row.
After first telling his passengers he was going to land in Yakutat, the pilot said he would continue to fly on at 12,000 feet.
"And then I heard the noise again," said Pease, who is the gas-pipeline advisor to Gov. Frank Murkowski.
"It was a vibration like you wouldn't believe," she said.
Once the plane leveled off, the flight became a visual treat as the plane flew low beside the coastal mountains on a brilliant day.
"A lot of people complimented the pilot," Pease said.
Also on Thursday, the pilot of Flight 162 from Anchorage to Fairbanks told air traffic controllers he was going to fly at a lower altitude, said Storm, of the FAA.
The cabin was properly pressurized, and no warning horn sounded, according to Tobin. The pilot's reason for flying at 10,000 feet was unavailable.
On Wednesday, Flight 43 from Anchorage to Bethel was diverted back to Anchorage less than 30 minutes after taking off because the altitude warning horn sounded, Tobin said. The passengers took another flight to reach Bethel.
Why the horn on Flight 43 sounded was still unknown, Tobin said.
Also on Wednesday, Alaska Airlines Flight 397 took off from Ontario International Airport in Southern California for a flight to Seattle but diverted to Los Angeles, 35 miles away, after an "initial indication (that) the cabin was pressurizing at a slower rate of speed than expected," Tobin said.
"We have concluded our initial investigation and determined that the pressurization system is normally functioning," she said. "We are always very conservative. Any time there is an initial indication (of a problem), we always take immediate action to put safety first."
The day before, Flight 100 from Portland to Denver returned to Portland 15 minutes into the flight after the passenger oxygen masks deployed. The airline is investigating why, according to Tobin.
An altitude warning alarm sounded when Flight 690 reached 33,000 feet, indicating the air pressure in the cabin was lower than it should be.
Earlier this year, Alaska ordered a fleet-wide inspection of its planes' air pressure systems after a series of similar cabin pressure problems.
Five passengers aboard an Alaska Airlines jet bound for Denver were treated by paramedics after the plane's automatic pressurization system malfunctioned.