What happened
An aircraft departed Agüehita, Sonora, Mexico, bound for Janos, Chihuahua, Mexico, without filing a flight plan. During the departure phase, the pilot's son observed a dark, threatening cloud bank near a mountain range in the direction of the flight path. The aircraft failed to arrive at its destination, prompting a search that was subsequently extended to the United States side of the border.
On January 15, 1982, a rancher discovered the wreckage scattered over an area exceeding one mile in length. Local residents reported that a severe snowstorm with heavy wet snow and reduced visibility was occurring at the time of the accident.
The investigation
An examination of the wreckage revealed that the tail assembly, right wing, approximately half of the left wing, and the windscreen had separated in flight. No evidence indicated a pre-impact malfunction or failure of the aircraft, engine, propeller, or accessories, except for the separated components which showed signs of in-flight pilot-induced overloads.
Findings
The investigation determined that during takeoff, the aircraft was approximately 547 lbs over its maximum gross weight limit, with the center of gravity approximately 2 inches behind the aft limit. The pilot was not rated for instrument flight. These conditions contributed to the structural failure in severe weather.
Safety message
Operating an aircraft significantly beyond its weight and balance limits, particularly without instrument ratings in adverse weather, creates unacceptable risks of structural failure.