What happened
On March 10, 2020, at 14:14 UTC, a Cessna 152, registration SP-KOG, departed from runway 28 at Warsaw Babice Airport (EPBC) for a training flight. The flight was being conducted by a student pilot under the supervision of an instructor. During the first turn following takeoff, the instructor noticed the engine RPM dropping to between 1700 and 1800 RPM, accompanied by irregular engine operation and noticeable vibrations.
The instructor took control of the aircraft and notified the airport services of an engine failure and the need to land on runway 10. The aircraft landed safely on runway 10 without further incident. Subsequent inspections by technical personnel, including an engine test run, revealed no mechanical malfunctions. A subsequent test flight conducted by another instructor also showed normal engine parameters.
The investigation
The PKBWL examined the meteorological conditions present during the flight. METAR reports from Warsaw Chopin (EPWA) indicated temperatures and dew points that were highly conducive to carburetor icing at all power settings. The investigation focused on why the crew did not recognize the symptoms of icing and why the engine performance degraded despite the lack of mechanical defects.
Findings
- The primary cause of the engine power loss was carburetor icing.
- Atmospheric conditions (temperature and dew point) were favorable for ice accumulation in the carburetor.
- The pilot failed to correctly identify the engine symptoms as indicators of icing, instead believing a mechanical engine failure had occurred.
- While the instructor had reviewed the weather forecast before the flight, they had not specifically analyzed the risk of icing formation.
Safety action
Following the incident, the instructor was briefed on the necessity of more thoroughly checking and analyzing meteorological conditions prior to every flight.