What happened
On 4 March 2022, a Cessna F172M, registration EI-DDC, was performing a general aviation flight from Navan Airfield, Co. Me/ath. After clearing frost from the wings, the pilot initiated a takeoff from Runway 27. Shortly after becoming airborne, the pilot noticed the airspeed was significantly lower than expected, indicating only 40 knots. To prevent a stall, the pilot attempted to land again, but the aircraft bounced upon touchdown. During the subsequent landing attempt, the aircraft veered right, struck a perimeter fence at the end of the runway, and came to rest in a nearby field. The pilot, the sole occupant, sustained no injuries, and the aircraft suffered minor damage.
The investigation
The AAIU examined the aircraft's performance, the pilot's experience, and the environmental conditions. The investigation noted that the pilot was more familiar with a different aircraft type and had very limited experience on the Cessna F172M. During pre-takeoff checks, the pilot observed that applying carburettor heat did not result in a noticeable change in engine RPM. Additionally, the investigation found that the pilot's takeoff technique involved placing both hands on the control yoke, leaving the throttle unguarded and without the use of the friction nut. Witnesses at the airfield also observed the aircraft flying at a high nose-up attitude and a reduced engine RPM.
Findings
Several factors contributed to the runway excursion:
- The pilot's lack of familiarity with the specific aircraft type and its cockpit layout.
- The likelihood that engine power decreased because the throttle crept backward due to vibration, as the throttle friction nut was not engaged and the pilot's hand was not on the lever.
- Environmental conditions, including a low dew point depression, were highly conducive to carburettor icing, which may have degraded engine performance.
- The aircraft became airborne at an insufficient airspeed; as it transitioned out of ground effect, increased induced drag prevented a stable climb.
- The combination of a bounced landing and reduced braking effectiveness on the wet grass made it impossible to avoid the perimeter fence.