What happened
On May 10, 2014, a Cessna 140A, registration PT-AGS, departed from the Cachoeira do Sul Aerodrome (SSKS) for a local flight instructor training mission. The aircraft was occupied by two crew members: an instructor and a student. Approximately 30 minutes into the flight, the crew lost control of the aircraft, which entered an abnormal state and collided with the ground. The impact destroyed the aircraft, and both pilots sustained fatal injuries.
Witnesses reported that the aircraft was flying at a low altitude and appeared to be operating with low engine power. The aircraft was observed performing a steep right-hand turn before entering a descending spiral, commonly known as a spin, leading to the impact.
The investigation
CENIPA's investigation focused on the flight maneuvers and the organizational environment of the operator, Aero Agrícola Santos Dumont Ltda. Investigators examined the aircraft's maintenance records, which were up to date, and confirmed the engine was functioning correctly, ruling out mechanical failure as a cause.
The investigation scrutinized the physiological state of the crew, noting that toxicological tests revealed the presence of alcohol in the instructor's blood and traces of cannabis in the student's urine. While the exact influence of these substances on pilot performance could not be definitively determined, the investigation noted that such substances can impair cognitive and psychomotor functions.
Furthermore, the investigation looked into the flight school's operational procedures. It was found that the instructor had limited experience in the instructor role and was performing his fourth instructional flight of the day. The investigation also identified a lack of standardized flight manuals and a lack of formal safety reporting (RELPREV) within the company.
Findings
- The primary cause of the accident was a cross-control stall leading to a spin, likely triggered when the student attempted a steep turn during a simulated emergency landing maneuver in an unprepared field.
- The instructor's inexperience in the instructor role may have delayed the recognition of the abnormal flight condition and the subsequent decision to take control.
- Organizational deficiencies, including a lack of standardized training parameters for unprepared field landings and inadequate supervision of instructor workload, contributed to the accident context.
- The absence of formal briefing and debriefing procedures may have hindered effective crew resource management and flight dynamics.