Trapped employee fell asleep in plane's cargo bay

CNN) - Getting caught napping on the job is never good. Getting caught napping on the job in the cargo hold of a plane takes it to a whole different level.

Alaska Airlines Flight 448 was just barely on its way to Los Angeles from Seattle-Tacoma International Airport on Monday afternoon when the pilot reported hearing unusual banging from the cargo hold.

"There could be a person in there so we're going to come back around," he told air traffic control.

The banging in the cargo hold did come from a person and he turned out to be a ramp agent from Menzies Aviation, a contractor for Alaska Airlines that handles loading the luggage, the airline said. The man told authorities he had fallen asleep.

It appears he was never in any danger.

The cargo hold is pressurized and temperature controlled, the airline said. The plane was also only in the air for 14 minutes.

What's that noise?

The passengers knew something wasn't right, almost as soon as the plane took off.

"All of a sudden we heard all this pounding underneath the plane and we thought there was something wrong with the landing gear," Robert Higgins told CNN affiliate KABC

The pounding grew louder.

"At that point, we started hearing yelling, screams for help, very, very faint," Jamie Davis said. "That's when we notified the flight attendant that there was somebody underneath us."

As the banging continued, a federal air marshal sprang into action.

"At some point, the marshal kind of made himself known," said Troi Ge. "He started banging back, and he yelled really loud and said, 'We're getting ready to land, hold on to something.'"

Emergency landing

The emergency landing spooked the folks aboard Flight 448.

Affiliate KOMO spoke to Marty Collins, another one of the passengers.

"We just took off for L.A. regular and then ... about five minutes into the flight the captain came on and said we were going back and we'd land within five to seven minutes, and we did," Collins said. "When we landed was when all the trucks and the police and the fire trucks surrounded the plane."

"I think it's scary and really unsafe, too," Chelsie Nieto told affiliate KCPQ. "Because what if it's someone who could have been a terrorist?"

Under investigation

The ramp agent appeared to be in OK after the ordeal.

He was taken to an area hospital as a precaution, the airline said. He passed a drug test and was discharged.

The employee started work at 5 a.m. and his shift was scheduled to end at 2:30 p.m., just before the flight departed.

"During a pre-departure huddle, the team lead noticed the employee was missing. The team lead called into the cargo hold for the employee and called and texted the employee's cell phone, but did not receive an answer. His co-workers believed he finished his shift and went home," the airline's blog said.

Alaska Airlines said it's investigating. The man had been on a four-person team loading baggage onto the flight.

All ramp employees have security badges, and undergo full criminal background checks before being hired, according to the airline.

After the delay, the flight with 170 passengers and six crew members on board made it to Los Angeles early Monday evening.

CNN's Greg Morrison contributed to this report.