Tokyo, Japan (CNN) -- A body was found in the landing gear bay of an airplane that arrived at Tokyo's Narita Airport Sunday, the airport announced.
The dead man was not carrying a passport or personal belongings, airport police said.
The man was of dark complexion and dressed in blue jeans and a red and dark blue long-sleeved shirt, police told CNN.
Police said he possibly froze to death and suffered a shortage of oxygen at high altitude, but did not provide a definite cause of death pending an autopsy.
A mechanic found the body in the landing gear bay, which was impossible to enter from the cabin, the airport said.
The Boeing 777, Delta Flight 59, which departed New York's John F. Kennedy International Airport at 12:53 p.m. ET Saturday arrived at Narita at 4:46 p.m. local time Sunday, the airport said.
"Delta is fully co-operating with the Japanese authorities, and there is (an) on-going investigation which is being led by the Japanese authorities. The airline has not issued an official statement at this time," a Delta representative told CNN.
