Dutch border police at Schiphol airport discovered a stowaway in the front wheel well of a cargo plane from South Africa on Sunday.

The man survived an 11 hour trip at sub-zero temperatures and was able to answer some basic questions as he was taken to hospital, the border police said on social media.

Most people who hide in wheel wells die during the the trip but scientists have not been able to figure out why some people manage to survive the freezing temperatures, which can go down to -63 degrees Celsius.

Some people may go into a form of hibernation, during which the body’s requirement for oxygen diminishes, experts think.

Some 130 wheel well stowaways have been documented but according to the Federal Aviation Administration the number might be higher because bodies have fallen out in remote areas or into the ocean.

Nothing is yet known about the man’s identity or the other circumstances surrounding the flight. The police are continuing its inquiries.