Officials noticed the panel was missing from the Boeing 747, one of two jetliners used by Prime Minister Shinzo Abe for foreign trips, after it flew from Tokyo to its base on the northern island of Hokkaido on Thursday, a spokesman for the Japan Air Self Defence Force (ASDF) said.
The part, measuring 38 cm (15 inches) by 20 cm, has not been found. It is an access panel near the pylon connecting one of the engines to the right wing.
The air force would conduct an investigation to determine why the panel had fallen off Abe’s plane, the ASDF spokesman said.
The two government jumbos left Tokyo on Friday carrying Abe, government officials and Japanese business representatives on a six-day trip to Eastern Europe, including stops in Estonia, Lithuania, Serbia and Romania.
More on Reuters