What It's Like to Be Trapped in a Cargo Hold

— -- The baggage handler who reportedly fell asleep in the cargo hold of an Alaska Airlines flight could have inadvertently taken a nap while waiting to load more luggage, according to one former pilot.

"This had to be while the loading had started," said ABC News aviation consultant John Nance. "Maybe they stopped and were waiting for another load of bags."

Nance previously flew the same model of plane for the same airline involved in Monday night’s incident, and he said that it would have been an uncomfortable experience for the baggage handler. Cargo holds in Boeing 737s are just filled with "all types of bags" and are not very high, he said.

"There's not enough room to stand up. You're leaning over," Nance said. "It’s very tough work. As a matter of fact, you get a lot of back injuries in this line of work."

Teams of three or four handlers usually work together to load "thousands and thousands" of pounds of bags into the cargo holds and sometimes can be left waiting for deliveries of bags for periods of time.

At least one member of the crew is tasked with crawling deep into the hold to move luggage along and maximize storage, which is why many baggage handlers wear knee protectors or knee pads.

"If you hit a pile of bags in the front and someone decided to crawl up and take a cat nap, or if they were waiting in there and just happened to fall asleep, you wouldn’t find them unless you went in there and got them," Nance told ABC News.

Once the plane took off with the unidentified handler inside, Nance said that the noise from the engines would have been extremely loud, even if the man was wearing headphones or earplugs like many baggage handlers regularly wear while loading luggage on and off planes.

"You'd want to have plugs on the ramp. That’s a job ender if you don’t, because you can damage your hearing in three days," Nance said. "Whether that contributed to the problem or not, we don’t know."

The handler reportedly began banging the top of the cargo hold, which is directly beneath the floor of the passenger cabin, to alert the passengers.

"It's entirely possible that one of the reasons for the frantic banging and yelling was that this poor guy didn't know that it was heated and pressurized," Nance said.

Aside from the mountains of bags, the only other company that the handler could have had in the hold were any pets that had been checked beneath deck, and there’s no way of knowing whether or not those animals would have been conscious or not. Airlines and vets tell pet owners not to drug their pets for flights, Nance said, but that doesn’t stop some from giving their animals medication anyway.