The incident Monday afternoon involved an MD-80 jet en route to Burbank, Calif. The plane landed safely at Sea-Tac and none of the 140 passengers or five crew members was hurt, Alaska Airlines spokeswoman Caroline Boren said.
Applause erupted onboard as the plane touched down with oxygen masks still dangling above nervous passengers.
Damon Zwicker had a video camera rolling inside the cabin and turned the camera on himself after the landing. "Well, catastrophe averted," he said looking into the lens.
Interviewed in Burbank, Calif. on Tuesday evening Zwicker and his girlfriend, Leslie Comstock, were still shaken up.
"There was a bang and the oxygen masks fell down... and I knew at that point that something was wrong," Zwicker said.
"It was absolutely the scariest thing I've ever had to go through in my entire life," Comstock said. "I felt like I was lucky to be alive."
The National Transportation Safety Board and the Federal Aviation Administration were investigating, along with the airline and the Port of Seattle.
A ramp worker has acknowledged he failed to immediately report striking the plane at the gate Monday with a baggage cart or baggage-belt machine, NTSB spokesman Jim Struhsaker said.
The worker told the agency that although the vehicle touched the plane, he was not aware he had dented it, Struhsaker said.
The bump created a crease in the plane's aluminum skin, which opened up into a 12- by 6-inch gash as the plane came under increased pressure at 26,000 feet, Struhsaker said.
On Tuesday, Alaska Airlines contacted the Port of Seattle "and asked our police department to take a hit-and-run report," port spokesman Bob Parker said Tuesday evening. "We're coming into this a full 18 hours after the fact. We got involved after Alaska Airlines reported a hit-and-run involving their airplane."
The worker was employed by Menzies Aviation, a British company that Alaska contracts with to provide baggage handling and other ramp services at Sea-Tac, Boren said. The employee was suspended Wednesday and other baggage handlers were given a safety briefing.
Alaska Flight 536 left the airport for Burbank just before 4 p.m. Monday. The flight crew reported a loss of cabin pressure about 20 minutes later, Boren said. Oxygen masks deployed for passengers and the plane made a rapid descent, landing at Sea-Tac just before 5 p.m., she said.
"My ears started popping and then the rapid depressurization of the plane occurred. And then a lot of white noise and a lot of engine noise, and you can't breathe, you're just gasping for air," passenger Jeremy Hermanns told KOMO-TV.
Hermanns took several pictures with his cell phone camera as flight attendants checked to make sure each passenger's oxygen mask was secure.
"You're not really thinking at that point," Hermanns said of the moment the masks popped down. "It was pretty chaotic."
The hole was on the right side of the plane between the forward and middle cargo holds, Boren said. It was about 4 feet beneath passenger windows.
"I can tell you that there was a ramp vehicle that did make contact with the aircraft prior to the aircraft leaving for Burbank," she said. She did not know the exact type of vehicle, the exact sequence of events of the contact being reported, nor the status of the worker involved.
About 430 Menzies workers provide services for Alaska at Sea-Tac, Boren said. Meetings were being held with them to review safety procedures, including the "rapid and thorough reporting" of incidents on the ground, she said.
"We're working with the NTSB to review all the information relative to this event," Boren said.
The plane was being repaired and should be back in service within a few days, she added.
Menzies Aviation did not immediately return a call for comment Tuesday night.
Last May, Alaska Airlines laid off nearly 500 baggage handlers and other ramp workers at Sea-Tac, saying it needed to trim costs amid rising fuel prices and fierce competition from low-cost carriers.
In a statement then, Alaska said hiring Menzies Aviation to provide those ramp services at the airport would save $13 million a year.
Alaska Airlines is the nation's ninth-largest carrier. Together with its sister airline, Horizon Air, it flies to more than 80 cities in the United States, Canada and Mexico.