What happened
On September 29, 2005, at approximately 12:30 UTC, a Helio Courier H 250, registration CS-ALE, was performing a demonstration flight from an improvised, unpaved landing strip at Herdade da Caneira, near Foz do Almofala, Almeirim.
The pilot initially attempted a south-to-north takeoff but aborted the run after realizing the aircraft was not accelerating sufficiently to clear trees at the end of the field. Deciding to use the opposite direction (north-to-south) to avoid disturbing people near a nearby hangar, the pilot began the second takeoff attempt using only about 300 meters of the available runway.
During the takeoff roll, the aircraft rotated at 40 MPH. Facing a large pine tree ahead and having not yet reached the recommended climb speed of 50–6/0 MPH, the pilot initiated a left turn to avoid the obstacle and attempt to regain airspeed. This maneuver caused the aircraft to lose vertical lift and airspeed, entering a state of power-off/low-speed descent. The aircraft subsequently struck the treetops of a hedge bordering a nearby stream, resulting in significant damage to the wings, landing gear, engine cowlings, and windshield. The two occupants (the pilot and a passenger) were uninjured.
The investigation
The GPIAAF investigation examined the aircraft's maintenance records, which showed the engine and airframe were well-maintained and in good condition. The investigation also analyzed the environmental and performance factors at the time of the accident.
Investigators noted that the takeoff surface was an unpaved, irregular field with grass and small stones, which increased rolling resistance compared to a paved runway. Furthermore, the ambient temperature of 28°C (ISA + 15) significantly degraded engine performance and increased the required takeoff distance. The investigation established that while the available 300 meters of runway might have been sufficient for a standard takeoff on a paved surface, the combination of high temperature, unpaved terrain, and the pilot's decision to use a shortened runway length contributed to the loss of performance.
Findings
- The primary cause of the accident was the pilot's decision and deficient piloting technique during takeoff, which led the aircraft into a power-inversion zone, preventing a positive climb gradient.
- The pilot did not utilize the full length of the available takeoff distance.
- High ambient temperatures (ISA + 15) reduced engine performance and increased the required takeoff distance.
- The irregular, unpaved surface of the landing strip increased resistance to acceleration.
- The pilot's attempt to turn away from an obstacle at a low airspeed prevented the aircraft from maintaining altitude or accelerating sufficiently to clear the trees.