What happened
On 13 September 2020, an Ikarus C42 FB80, registration G-CFHP, was conducting a training exercise at Porthtowan, Cornwall. The commander, a flight instructor, was demonstrating the 'Beat Method' for a practice forced landing (PFL) to a student. The procedure involved flying a figure-of-eight pattern to lose altitude before establishing a glide approach to the private airstrip.
During the maneuver, the commander deployed full flaps early to steepen the descent because the aircraft appeared high for the remaining distance. While flying the into-wind track, the pilot became preoccupied with avoiding domestic power cables located near the runway threshold. This focus caused the aircraft to cross the cables at an altitude of approximately 30 to 40 ft agl, lower than originally intended.
To align with the runway, the commander initiated a right turn with a 35° bank angle. During this maneuver, the right landing gear struck a 5-foot-tall perimeter fence. The impact abruptly turned the aircraft 90° to the right and forced it into a heavy ground impact. The collision resulted in no injuries to the two occupants, though the aircraft suffered extensive damage to the engine cowling, both wings, and the nose landing gear.
The investigation
The investigation examined the flight path, the pilot's decision-making, and the environmental factors at the airstrip. The AAIB established that the early use of full flaps significantly steepened the glide angle, leaving the pilot with limited options to adjust the approach height later.
Investigators also analyzed the pilot's mental state, identifying a phenomenon known as cognitive tunnelling. The commander admitted that his intense focus on clearing the power cables caused him to lose awareness of the aircraft's overall flight path and the presence of the student. Furthermore, the investigation noted that the pilot delayed the turn to final to ensure the cables were cleared, which placed the aircraft off-track and necessitated a sharper, more aggressive turn at a very low altitude.
Findings
- The early deployment of full flaps removed the ability to use flap adjustments to modify the glide path later in the approach.
- The pilot experienced cognitive tunnelling, focusing so intently on the power cables that he failed to recognize the flight path was becoming unsafe.
- The pilot did not initiate a go-around despite the aircraft being lower than planned.
- The aircraft was positioned south of the intended runway track due to a delayed turn, requiring a steeper bank angle that increased the rate of descent.