Authorities are still investigating how a 16-year-old teen, who snuck past airport security and climbed into the wheel well of a Hawaiian Airlines plane, survived the flight from San Jose to Maui on Sunday as the temperature in the atmosphere reached an estimated 80 degrees below zero.

Federal Aviation Administration officials said they believe the teen stowaway could have stayed warm because of the plane's landing gear including the heat from hydraulic lines and heat emitting from the tires, the Los Angeles Times reported.

The FAA also said a stowaway would likely begin to loose consciousness because of low oxygen levels as the plane gains its altitude. A stowaway could develop hypothermia, as a result of the extreme cold, which would preserve the central nervous system and then resolve when the plane begins its decent.

FBI spokesman Tom Simon said they are still unsure if that is exactly what happened to the teen, who hopped aboard Hawaiian Airlines Flight 45 at Mineta International Airport in San Jose before taking off to Maui's Kahulu Airport.

"How he survived, I don't know," Simon said. "It's a miracle."

Simon said the teen from Santa Clara, Calif. was unconscious most of the flight, which reached an altitude of 38,000 feet during the 5-1/2-hour ride.

"I imagine he must have blacked out at about 10,000 feet," Simon said. "The air is pretty thin up there."

Simon said the teen had lost consciousness and didn't come to until an hour after the plane landed Sunday morning.

The teen was seen wandering on a ramp by Hawaiian Airlines personnel after he regained consciousness and jumped down on to the tarmac.

Hawaiian Airlines spokeswoman Alison Croyle said in statement Sunday night that once the company's personnel saw the teen, they notified security.

"Our primary concern now is the well-being of the boy, who is exceptionally lucky to have survived," Croyle said.

Simon said the teen, who boarded the aircraft because he was running away from home, was not deemed as a threat by authorities. He passed medical examinations before being handed over to the Hawaii Department of Human Services.