Jumping a deteriorating airport fence, running across the airport unobserved in the darkness and climbing into the wheel well of a parked Boeing 767, as a California teenager did Sunday, is not all that difficult, according to experts, but surviving the trip -- in this case, a 51/2-hour flight from San Jose, Calif., to Maui, Hawaii -- is extraordinary.
"I just assumed that everybody who did this died," airport consultant Richard Marchi said.
Most do, but the 15-year-old boy, who hid in one of the wheel wells for the main landing gear on the plane, woke up after it landed and walked out onto the landing field, where he was noticed by the Hawaiian Airlines ground crew and eventually turned over to state child welfare authorities. He had apparently spent most of the flight unconscious in the freezing, low-oxygen, wheel storage compartment.
Officials in Hawaii would not describe the condition of the stowaway Monday, but did say he was from Santa Clara, Calif.; had been traveling with no identification; and had run away from home after a dispute with his family.
"Officials have notified the boy's family that he is safe," the Office of Child Welfare Services said in a statement. It added that the office would "enlist the help of all necessary agencies to ensure the boy's safe return to his home in California."
Boeing opted not to discuss the incident; a spokesman said the company did not want to "provide any information that might encourage such extremely dangerous and illegal activity."
Airport security cameras caught what seems to have been the boy climbing the fence at Mineta San Jose International Airport and crossing the tarmac to reach the airplane, authorities said. They said the boy, whose name was not released, did not remember any of his ordeal.
The plane landed in Maui at 10:30 a.m., but the boy did not emerge from the wheel well until 11:30, said Tom Simon, a special agent in the FBI's Honolulu office. He said the boy wore a hoodie and long pants and "no special gear."
Because he was not conscious, "he didn't have a compelling story about his harrowing ordeal," said Mr. Simon, who added that the boy was "lucky to be alive."
In fact, the boy is in the minority among wheel-well stowaways. According to the Federal Aviation Administration, since 1947, worldwide, 105 people have stowed away on 94 flights in the space where the main landing gear or the nose wheel fits. The cold and low oxygen levels at cruise altitudes killed 80 of them, for a mortality rate of 76 percent. Often their bodies were found miles from the arrival airport, below the spot where the pilots opened the doors and lowered the gear for landing.
The landing gear of a 767 holds the belly of a plane about 6 feet off the ground, so the space into which the wheels nestle in flight is fairly large. The wheel well has aluminum walls, with several hydraulic and electrical lines running through it, which could provide a place to nestle, but anyone who tried to lie on the doors while they were closed would fall out when the pilot started the landing procedure.
Big airliners commonly cruise at altitudes as high as 38,000 feet, where the oxygen is only about 20 percent of what it is at sea level, and the temperature approaches 80 degrees below zero. Death is common at cruise altitudes because the air is so thin that outside the pressurized portion of the fuselage, people can suffer nitrogen gas embolisms, known to sea divers as "the bends."
The barrier the stowaway presumably breached is "an eight-foot fence with three strands of barbed wire," said Mr. Marchi, the consultant, who is a former senior official with Airports Council International, a trade group. "I probably could have done it when I was 18."