Cessna 172 Forced Water Landing on Sulzberger See

Casualties unknown • Kempten/Sulzberger See, DE

A private flight involving four occupants ended in an emergency water landing on Sulzberger See after a takeoff attempt failed to gain sufficient altitude.

What happened

On May 9, 2021, a Cessna F 172 H departed from Kempten-Durach airfield for a private flight. Prior to departure, the aircraft had been refueled with automotive unleaded gasoline (Super Plus) at the airfield. During the takeoff roll on grass runway 17, the pilot utilized a flap setting of approximately 30 degrees. While the aircraft achieved liftoff at roughly 65 knots, it failed to maintain a positive rate of climb after passing a nearby highway.

As the aircraft's altitude decreased, the stall warning activated. Unable to find a suitable landing field due to the hilly terrain, the pilot executed an emergency water landing on the Sulzberger See. The aircraft impacted the water with a slight right bank and a yaw to the right, sinking in less than five minutes. The impact caused the windshield to shatter, and the occupants had to work together to evacuate the cabin before being rescued by bystanders.

The investigation

The BFU examined the aircraft, the site of the accident, and the circumstances surrounding the takeoff. Investigators recovered the aircraft from a depth of 8 meters. Technical inspections of the Cessna F 172 H revealed significant structural damage, including deformed wings, a broken right wing strut, and a partially detached engine mount. The investigation also reviewed the aircraft's weight and balance, determining a takeoff mass of 1,037 kg, which was within the permitted limits but near the maximum takeoff weight of 1,043 kg.

Findings

  • The aircraft was configured with flaps set to approximately 30 degrees during takeoff, which increased aerodynamic drag and significantly reduced the climb performance.
  • The aircraft was operating at a high density altitude of approximately 4,200 ft, further impacting engine and aerodynamic performance.
  • The takeoff weight of 1,037 kg was near the maximum allowable limit of 1,043 kg.
  • There were issues regarding the documentation and verification of a Supplemental Type Certificate (STC) required for the use of automotive gasoline in the engine.

Probable cause

The primary cause of the accident was the use of an excessive flap setting during takeoff, which created enough drag to prevent the aircraft from maintaining a safe climb gradient, leading to a loss of altitude and the subsequent forced water landing.

Frequently asked questions

What happened in the 2021-05-09 Reims Aviation Cessna Cessna F 172 H accident near Kempten/Sulzberger See, DE?

A private flight involving four occupants ended in an emergency water landing on Sulzberger See after a takeoff attempt failed to gain sufficient altitude.

What aircraft was involved and where did it happen?

The accident on 2021-05-09 involved a Reims Aviation Cessna Cessna F 172 H, at Kempten/Sulzberger See, DE.

What was the probable cause of the accident?

The primary cause of the accident was the use of an excessive flap setting during takeoff, which created enough drag to prevent the aircraft from maintaining a safe climb gradient, leading to a loss of altitude and the subsequent forced water landing.

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