How did teen stowaway survive 5-1/2 hour flight to Hawaii in wheel well?

A 16-year-old runaway hopped the security fence at San Jose airport in northern California, climbed into the wheel well of a Hawaiian Airlines flight, and was found more than six hours later wandering around the tarmac at Maui's Kahului airport, the FBI said Sunday.

The extraordinary journey is confounding aviation experts, who say they've never heard of such a thing before. But the FBI says it has video of the teen climbing the fence in San Jose. "His story checked out," Tom Simon, an FBI spokesman, told Reuters.

The boy apparently ran away from home after a fight with his parents, according to the FBI. He has not been charged with a crime and is now in the custody of child protective services in Hawaii. 

Airplane stowaways have been known to survive before. A teen in Nigeria survived in a wheel well during a domestic flight in 2013. But that journey was only 35 minutes and stayed at comparatively low altitudes. 

The Hawaiian Airlines flight reached 38,000 feet and was 5-1/2 hours long. At such altitudes, oxygen levels are low and temperatures can reach minus 40 degrees Fahrenheit. Authorities say the boy was passed out for most of the flight and awoke an hour after landing. But they said he was unharmed.

ABC News cites a Federal Aviation Administration report that estimates that the chances of surviving as a wheel-well stowaway on a commercial aircraft are about 24 percent. Radiant heat from the plane's hydraulics as well as the wheels themselves can help warm the compartment, the FAA notes. And the plane's gradual ascent and descent allow the body to adjust to the extremes of cold, lack of oxygen, and low pressure.

But some experts expressed shock. Analyst Peter Forman told KHON-TV:

The odds of a person surviving that long of a flight at that altitude are very remote, actually. I mean, you are talking about altitudes that are well above the altitude of Mount Everest. And temperatures that can reach 40 degrees below zero. … A lot of people would only have useful consciousness for a minute or two at that altitude. For somebody to survive multiple hours with that lack of oxygen and that cold is just miraculous. I’ve never heard of anything like that before.

Other known stowaways have died, including a 16-year-old on a flight from Charlotte, N.C., to Boston in 2010, and a man found on a London street in 2012, who is believed to have fallen out of his plane's wheel well as the Angola-to-London flight descended for landing. It was unclear whether he was alive when he fell.

In San Jose, a local congressman, Rep. Eric Swalwell, has raised questions about security: [Editor's note: The spelling of Eric Swalwell's name has been corrected.]