Cessna 177B N123DS accident near Watkinsville, Georgia

Probable cause

The pilot’s spatial disorientation and subsequent loss of airplane control, which resulted in an in-flight overload separation of the right wing during the uncontrolled descent.

NTSB analysis

The pilot was approaching his destination airport under instrument flight rules (IFR) and in instrument meteorological conditions. The air traffic controller issued a northeasterly heading for the pilot to intercept the final approach course. The controller then informed the pilot that he would be vectored through the final approach course to accommodate preceding traffic. The controller then instructed the pilot to turn right to a southwesterly heading. The controller observed the airplane descending and a low altitude alert activated. The controller instructed the pilot to maintain 3,000 ft. The pilot read back the altitude; this was the last transmission from the pilot. The controller then instructed the pilot to fly a westerly heading and no further responses were received from the pilot. Track data revealed that the airplane continued in a right, descending turn until radar contact was lost. The outboard section of the right wing and the right flap separated in flight and the airplane impacted a farm field.

Postaccident examination of the airframe, engine, and propeller did not reveal evidence of a pre-existing mechanical malfunction or anomaly that would have precluded normal operation. All fracture surfaces on the separated right wing section displayed fracture features that were consistent with overstress-induced separation. The weather conditions at the time, in addition to the successive heading changes given to the pilot, were conducive to the onset of spatial disorientation.

Although one of the pilot’s toxicology specimens tested positive for gabapentin, a disqualifying medication that can cause dizziness, drowsiness, blurred vision, and sedation, the pilot’s passenger (his spouse) was prescribed the medication and intermingling and contamination of the samples were possible; therefore, it is unlikely that the pilot had taken the medication.

Text from the NTSB. Open the NTSB docket for ERA23FA209 for the full record.