It is highly likely that a Japanese F-35 stealth fighter jet that crashed into the Pacific Ocean did so because the pilot lost “spatial awareness”, officials said.
In April, the Lockheed Martin aircraft disappeared from radar screen during an exercise.
Some debris and the remains of the 41-year-old pilot have been discovered.
Officials said F-35 flights, which had been halted, will resume after additional training.
This was the first reported crash involving an F-35A, according to Japan’s Air Self Defense Force (JASDF.
“It seems highly likely that the pilot was suffering from vertigo and was unaware of his condition,” the JASDF said in a press release.
The plane, which was less than a year old, crashed 28 minutes after taking off from Misawa air base in Aomori prefecture.
Officials believe the aircraft came down at a speed of about 1,100km/h (683mph).
The pilot gave no indication he was in trouble and there is no evidence he tried to eject his seat. The airforce has not recovered any intact data from flight data recorders.