What happened
On the morning of June 8, 2012, a Schweizer G 164 A (registration F-GTDJ) departed from Montpellier-Candillargues for an agricultural spraying mission over a field near Saint-Gilles. The flight path was oriented southeast/northwest, adjacent to the Rhône canal, with a 40-meter hill located at the northwest end of the work area.
During the initial pass, the pilot maintained an altitude of approximately 5 meters at an indicated airspeed of 90 knots. Upon reaching the end of the pass, the pilot initiated a right-hand climbing turn toward the hill without adjusting engine power. Believing sufficient altitude had been gained, the pilot leveled the aircraft and began a left-hand turn. As the airspeed dropped to 80 knots, the pilot realized the altitude was insufficient and attempted to recover by pulling back on the controls and increasing the bank angle. This maneuver resulted in an aerodynamic stall. The aircraft struck vegetation before impacting the surface of the canal. The pilot successfully evacuated the aircraft and swam to a ladder to exit the water.
The investigation
The investigation focused on the pilot's flight parameters and the aircraft's instrumentation. The aircraft was not equipped with an artificial horizon, and the stall warning consisted only of a red cockpit light without an accompanying audio alert. The pilot relied on external visual references to estimate the aircraft's attitude.
Investigators examined the pilot's experience, noting 1,912 total flight hours, with 118 hours on this specific type. The investigation also reviewed the Particular Operations Manual (POM), which mandates reconnaissance flights to identify obstacles and requires that turns be executed without risk, adapted to the aircraft's weight and daily conditions.
Findings
- The primary cause of the accident was insufficient monitoring of flight parameters, specifically airspeed, during a climbing turn.
- The pilot's choice of maneuver was inappropriate given the surrounding terrain and the proximity of the hill.
- The low altitude of the flight prevented the pilot from recovering control following the stall.
- The presence of the nearby hill may have distorted the pilot's perception of the horizon, potentially leading to an incorrect estimation of the aircraft's attitude.
- The pilot failed to notice the visual stall warning while focused on external landmarks.