What aircraft was involved and where did it happen?

The accident on 2021-02-27 involved a Cessna 150L, registration OK-MRK, at pole jižně od obce Hostim, CZ.

What was the probable cause of the accident?

The accident was caused by the formation of ice in the carburetor, which led to a loss of engine power. This occurred because the pilot operated in high-humidity, near-freezing conditions without the carburetor heat activated.

Carburetor Ice Leads to Emergency Landing in Cessna 150L

A Cessna 150L experienced engine power loss due to carburetor icing, resulting in an emergency field landing and aircraft inversion near Hostim.

What happened

On February 27, 2021, a Cessna 150L, registration OK-MRK, was conducting a recreational flight from Sazená airport. The flight plan included a touch-and-go landing at Plzeň-Líně and a transit through the Prague Ruzyně CTR.

During the flight near the SIERRA waypoint, the pilot experienced a gradual loss of engine power. Although the pilot attempted to increase power by advancing the throttle, the engine failed to respond adequately. After communicating with air traffic control and being directed toward Bubovice airport, the pilot determined that a forested hill prevented reaching the intended destination. Consequently, the pilot decided to perform an emergency landing in a field near Hostim.

Upon touchdown in the soft, saturated terrain, the nose gear collapsed. The aircraft bounced and subsequently overturned, landing upside down. The pilot and one passenger were able to exit the aircraft safely, and no injuries were reported.

The investigation

The ÚZPLN investigation examined the aircraft's maintenance history, the pilot's qualifications, and the prevailing meteorological conditions. Investigators analyzed the engine performance and the pilot's use of cockpit procedures during the emergency. The investigation also reviewed the operator's safety management system, specifically how hazards are identified and recorded in their risk library.

Findings

The primary cause of the accident was engine power loss caused by carburetor icing.
The atmospheric conditions—characterized by temperatures slightly above freezing (approximately 2°C) and high humidity (around 87%)—created a very high probability for ice formation within the carburetor.
Following a touch-and-go landing at Plze and, the pilot had deactivated the carburetor heat to ensure full power availability for departure but failed to reactivate it for the subsequent leg of the flight.
The pilot focused on reaching an airfield and did not utilize any emergency checklists or documentation to attempt to restore engine power during the descent.
The aircraft was destroyed due to the impact of the propeller with the ground and the subsequent inversion; the damage was deemed uneconomical to repair.
The operator's risk management system was found to use broad hazard categories that could potentially obscure specific operational risks, such as carburetor icing.