Delta Air Lines Flight 59 traveling from New York to Tokyo on Sunday night held a surprise for maintenance workers – a dead body of a man. The man had a dark complexion and was wearing blue jeans and a red and blue long-sleeved shirt. Japanese authorities are seeking US help to identify the man, as there were no personal belongings or a passport with him when they found him.

The body of the man was found by a mechanic inside the storage compartment door for the landing gear on a Boeing 777. The aircraft had been taken to a freight area after letting the passengers off at the gate. Airport police said that the body didn’t appear to have any external injuries, but there were signs of frostbite, which may have occurred while the jet was flying. However, there has been no official report of cause of death.

Yoshimi Ichihara, the spokesman for Narita Airport police, said that doctors think the man froze to death and struggled from lack of oxygen since the plane was more than 30,000 feet in the air. He added that any belongings the man was carrying with him probably fell out over the ocean when the landing gear opened.

There is enough room in the main housing compartment of the landing gear on a plane for a person to hide in. However, while the cabin of the aircraft is pressurized, the landing gear area isn’t. There have been many cases of stowaways hiding there and dying during the journey because of the lack of oxygen and freezing temperatures.

A representative for Delta Air Lines said that the airline is fully co-operating with authorities in Japan, and there has been an investigation launched. The carrier hasn’t issued an official statement yet.