What happened
On January 29, 2015, a Cessna 150M, registration PT-WGV, was conducting a visual navigation training flight from São José dos Campos to Itanhaém, Brazil. The crew, consisting of an instructor and a student pilot, was cruising at 5,500 feet over the coast near Guarujá when the engine began to exhibit RPM fluctuations.
As the engine power continued to drop, the engine eventually stopped functioning entirely. The instructor took control of the aircraft and initiated an emergency landing at the Santos Air Base (NuBAST). Despite the engine failure, the aircraft sustained no damage, and both occupants remained uninjured.
The investigation
CENIPA investigators examined the aircraft's systems, including fuel, lubrication, magnetos, and spark plugs. Post-incident testing, which included two engine runs, showed that all systems were operating within manufacturer specifications, with no mechanical defects found.
The investigation focused on the environmental conditions and cockpit procedures. The aircraft was flying in a high-humidity coastal region, a condition highly conducive to carburetor icing. Investigators noted that the pilot observed the initial RPM drop but failed to apply carburetor heat as prescribed by the emergency procedures. Furthermore, the instructor did not utilize the required emergency checklist, opting instead to rely on personal knowledge of the procedures. The student pilot, while qualified, did not intervene or question the omission of the checklist.
Findings
- Carburetor icing was the inferred cause of the engine failure, facilitated by high humidity at cruise altitude.
- Pilot error in judgment, specifically the failure to use the emergency checklist.
- Omission of critical procedures, as the pilot did not activate the carburetor heat following the initial engine fluctuation.
- Inadequate situational awareness regarding local landmarks, as the instructor initially considered an emergency water landing because they did not recall the proximity of the Santos Air Base.