Air force spokesman AM Monthon Sutchukorn said two L39 trainers had taken off for a land attack exercise. One returned for an emergency landing. The jet skidded along the runway and finally came to rest on the grassed area alongside it.
The two crew were safe. The two jets were based at Wing 41 in Chiang Mai.
They were taking part in Cope Tigher 2014, a joint training exercise involving Thailand, the US and Singapore
Air force investigators were dispatched from Don Mueang determine the cause of the incident.