How did a flight stowaway survive against the odds?

CTV News Channel: How did teen stowaway survive? Sarika Sehgal on how a boy’s survival for five hours at 38 000 feet without oxygen or heat has stunned everybody.

A trip in an airplane’s wheel well is usually fatal, despite one teen’s story of survival over the weekend, experts say.

The 16-year-old, who flew from San Jose, Calif., to Maui on Sunday, could have been “completely mangled and killed,” but he survived the trip apparently unharmed.

While it’s not unheard of for stowaways to bypass security, and the ticket counter, and hide in a plane’s wheel well, it is extremely rare to survive the journey.

The wheel well is where landing gear is stowed during the flight. Temperatures can plummet to -60 Celsius, one of several factors that can lead to certain death.

“The fact that he made it through is quite impressive,” pilot and aviation analyst Marc-Antoine Plourde told CTV News Channel on Monday. “The fact he survived with all the challenges of being in a wheel well beats all the odds.”

The first challenge, Plourde noted, is getting past security and onto the tarmac, and then into the wheel well. Security footage at Mineta San Jose International Airport showed the boy hopping a fence and making his way to Hawaiian Airlines Flight 45 uncontested. Airport security is reportedly working with the FBI and the U.S. Transportation Security Agency to review security at Mineta.

The next challenge, according to Plourde, is to survive the retraction of the landing gear once the plane is in the air.

“With the retraction of the landing gear, he could have been completely mangled and killed by the crushing landing gear retracting,” Plourde said.

As the airplane climbs, the air gets thinner and the temperature plummets and two conditions -- hypoxia and hypothermia -- make it very unlikely for a stowaway to survive.

“The air is so thin at these altitudes that hypoxia is certainly a threat to his life,” Plourde says. The symptoms of hypoxia begin with light-headedness, fatigue, a tingling or numbness in the extremities and nausea. As severe hypoxia kicks in, hallucinations, a quickening heart rate and an inability to breath eventually lead to death.

At such low temperatures, hypothermia also sets in. A stowaway may for a while be warmed by the heat from the tires, which become hot during takeoff, or from warm pipes that are carrying hydraulic fluid through the wheel well, according to the U.S. Federal Aviation Administration.

“These heat sources are progressively diminished as flight at altitude proceeds,” the FAA says.

The stowaway “is unconscious” by the time the landing gear comes out as the plane prepares to land, Plourde says. “Chances are, and we’ve seen that in the past, he would just fall out.”

A stowaway can regain consciousness and avoid plummeting to his or her death, the FAA points out. “A gradual rewarming occurs, along with reoxygenation,” as the plane begins its descent.

“If the individual is so fortunate as to avoid brain damage or death from the hypoxia and hypothermia, cardiac arrest or failure on rewarming…some progressive recovery of consciousness occurs, perhaps in the period before landing, or at a time after landing.”

The stowaway on Sunday’s flight to Maui lost consciousness during the flight and only emerged from the wheel well about an hour after the plane landed from its more-than 5 hour flight to Maui.

Other stowaways that have survived have mostly been on short-haul flights, where the plane would not have climbed to a very high altitude.

Others have not been so lucky, with stowaways falling to their deaths from wheel wells as the plane took off or landed.

In Sept. 2012, police in London suspected that a body found on a residential street in the city’s south-west end had fallen from a plane that was landing at nearby Heathrow Airport. A handful of bodies have turned up on city streets around Heathrow over the years, and authorities believe they were stowaways in the absence of any other evidence.

In 2010, the body of a 16-year-old American boy was found along the flight path to Logan International Airport in Boston. The boy is believed to have been hiding in the wheel well of a US Airways flight from Charlotte, N.C.

The number of stowaways over the years is impossible to count, the FAA notes.

“Some successful stowaway flights may be unknown, the travellers recovering at the destination with the help of ‘Good Samaritans,’” the agency notes.

“It is also likely that various unsuccessful attempts were never documented (or known), the bodies falling into an ocean, or into a remote land area.”