On December 30, 1986, an American Aviation Corp. (aac) AA-1A (registration N9493L) was involved in an aviation accident near Robertson, TX. Investigators recorded the probable cause as: The pilot's failure to maintain control of the aircraft while maneuvering near an obstruction, which resulted in a loss of control and subsequent impact with the ground. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Witnesses observed an aircraft circling a tall oil rig before it descended from sight and began spinning prior to ground impact. No mechanical failure was found.
What happened
Multiple witnesses reported observing the aircraft maneuvering around the top of a ninety-four-foot-tall oil well workover rig. As the aircraft circled, it eventually descended below the observers' line of sight. A separate witness located approximately one mile away noted that the aircraft began spinning before impacting the ground.
The investigation
Investigators examined the wreckage and conducted tests to determine the cause of the accident. No evidence of any malfunction in the engine or flight controls was found during the inspection process.
Probable cause
The pilot's failure to maintain control of the aircraft while maneuvering near an obstruction, which resulted in a loss of control and subsequent impact with the ground.