What happened
On November 9, 2008, a Cessna 150G, registration OK-WKF, was performing a solo cross-country flight from LKSZ to LKJC as part of a PPL(A) training program. While flying near Mšeno at approximately 1,600 ft AMSL, the pilot experienced a sudden drop in engine RPM from 2,200 to 1,800, accompanied by heavy vibrations and an audible change in engine running characteristics.
In response to the power loss, the pilot applied full carburetor heat. However, the engine failed to respond to throttle adjustments, and RPM continued to decline toward 1,600. Due to the rapidly decreasing altitude and the lack of engine response, the pilot decided to perform an emergency landing in a field approximately 1 km south of Mšeno.
Upon touchdown, the aircraft's nose wheel contacted the ground after an initial 8-meter rollout. Because the field had been recently plowed and was saturated from heavy rain, the landing gear dug into the soft soil. This caused the aircraft to decelerate abruptly, veer to the right, and strike the ground with the propeller, resulting in a bent propeller blade and damage to the engine mount and firewall. The pilot sustained no injuries.
The investigation
The ÚZPLN investigation examined the meteorological conditions, the aircraft's maintenance history, and the pilot's actions. Investigators noted that the ambient temperature was approximately 10–14°C with a dew point of around 6° and high humidity following recent heavy rainfall. The investigation also reviewed the aircraft's engine performance and the pilot's training records, noting that while the pilot was qualified for solo flight, they had not previously encountered such severe engine roughness.
Findings
- The primary cause of the engine power loss was carburetor icing.
- The pilot applied carburetor heat too late, after the ice had already significantly impacted engine performance.
- The pilot likely failed to sufficiently account for the high probability of icing given the specific combination of low power settings, high humidity, and ambient temperature.
- The damage to the aircraft's nose gear, engine mount, and propeller was caused by the low load-bearing capacity of the saturated, plowed soil.