History of the Flight
On 23 November 2021, at around 12:00 local time, a Piper PA-18 "Super Cub" registered F-GNMD, operated by Aéroclub Aquitaine Hydravions, was performing water landing exercises on Biscarrosse Lake. The pilot, accompanied by one passenger, had taken off from Biscarrosse Parentis aerodrome at about 11:20. During the flare of the ninth water landing, the pilot felt the right wing sink. The aeroplane pitched nose-down and turned to the right. The pilot was unable to regain control. The floats ruptured on contact with the water surface. Both occupants evacuated and inflated their life jackets. The aeroplane sank quickly. The pilot used his mobile phone to raise the alarm. Another seaplane arrived approximately 30 minutes later, and the occupants climbed onto its floats. Emergency services arrived about one hour after the accident.
Additional Information
Aeroplane Information
The PA-18 had a total fuel capacity of 136 litres. Maximum permitted take-off weight on floats was 906 kg, and maximum landing weight 860 kg. After adding 47 litres to 40 litres remaining, the fuel on board was 87 litres. The club estimated take-off weight at 913 kg, a slight overload of 8 kg. At the time of the accident, after 30 flight minutes, weight was about 900 kg, an overload of 39 kg. The centre of gravity was aft but within limits.
Pilot Information
The 66-year-old pilot held a Private Pilot Licence (Aeroplanes) with valid SEP, SEP(sea), and mountain ratings. He had 683 total flight hours, 21 in seaplanes. He obtained his SEP(sea) rating in December 2017, revalidated in December 2019. After 33 months without flying a seaplane, he performed a 47-minute supervised flight the day before the accident, including nine water landings.
Operator Information
The operator's seaplane pilot manual specified: flaps to first notch for water landing, final approach speed 55-60 mph, maintain smooth slope and approach attitude, adapt engine power, avoid major attitude variations. The flare starts with flare attitude to contact water at the step, maintaining power; power should not be reduced to idle during flare. The manual stated to leave fuel tanks half full for subsequent flights.
Meteorological Information
Météo-France estimated wind from 70° at 10-15 kt, CAVOK, temperature 10°C.
Statements
The pilot stated he initiated the flare at an estimated height of 5-10 metres with slight nose-up attitude, reducing power to idle. Shortly after, the right wing suddenly sank, then the aeroplane pitched nose-down in a right turn. Despite left stick and increased power, he could not regain control. He did not feel tired but thought he might have lost focus. He had not completed a weight and balance sheet, relying on the operator's instruction to not fill tanks beyond two-thirds. He noted a gyroplane had encountered wind shear earlier, and water had become slightly choppy.
The operator's flight safety manager stated that the number of water landings in the supervised flight seemed too many for the short duration.
Survival Aspects
No witnesses were present, but fishing boats were within 300 m. The pilot carried a mobile phone in a waterproof pouch as per operator procedure, enabling him to call for help. A seaplane landed nearby about 30 minutes later. The occupants climbed onto its floats and waited for a rescue boat another 30 minutes later. The pilot and passenger suffered from hypothermia.
Conclusions
During the flare, the pilot lost control of the seaplane. The sinking of the right wing and ineffective ailerons suggest an asymmetric stall. The pilot could not regain control before water contact. The floats ruptured, and the aeroplane sank quickly. Contributing factors include a possible stall from premature nose-up attitude with total power reduction at a weight slightly above maximum, and repetitive exercises combined with lack of recent seaplane experience that may have reduced vigilance.