What happened
On the afternoon of the incident, an EC-121R, registration 67-21493, operating as callsign "BATCAT 21" for the 554th Recon Squadron, was prepared for a combat tactical mission from Korat, Thailand. Following engine start and taxi procedures, the aircraft received takeoff clearance from Korat Tower at 15:54. During initial communications with departure control, the crew inquired about a nearby thunderstorm cell. While the controller initially instructed the aircraft to maintain runway heading before providing vectors, the crew later requested a right turn due to significant turbulence.
Shortly after becoming airborne at 15:58, the aircraft experienced severe atmospheric disturbances. The EC-121R impacted the ground in a rice paddy with its landing gear retracted and engines at maximum takeoff power. Traveling at a ground speed of 221 knots, the aircraft struck various obstacles including dikes and tree stumps, which caused the disintegration of the wings and propellers. The wreckage eventually struck a tree, resulting in an explosion, before the fuselage tumbled down a hill and overturned.
Findings
Investigations into the accident determined that the aircraft encountered a powerful downdraft and intense wind shear at an altitude of approximately 500 feet, roughly two and a half miles from the departure point. The most critical factor was a rapid shift in relative wind from a 20-knot headwind to a tailwind of at least 20 knots. As the aircraft descended into the lower altitudes, it encountered even stronger surface winds, estimated by witnesses to be a 60-knot tailwind, which contributed to the loss of control and subsequent impact.