What happened
On 25 July 2018, a Grumman AA5-B was performing a proficiency check for the revalidation of a single-pilot aeroplane rating at Aérodrome de Namur. During the final approach, the aircraft maintained excessive airspeed and altitude, causing it to float above the runway surface. The aircraft eventually touched down significantly far down the runway, between the one-third and one-half marks.
As the aircraft continued along the runway, the pilot expressed an intention to execute a go-around. However, the flight examiner, noting that the engine RPM had not returned to idle, determined that a go-around was no longer a viable option. The examiner took control of the aircraft, applied full braking, and attempted to stop the plane. The aircraft overran the runway and entered a harvested field, striking a ditch in the process. The two occupants of the Grumman AA5-B were uninjured, though the aircraft sustained damage to the propeller and the nose landing gear assembly.
The investigation
Investigators examined the aircraft's mechanical condition and the environmental factors present during the landing. Maintenance inspections revealed that the transversal torque tube supporting the nose landing gear had been damaged, and the nose gear had impacted the engine cowling. The investigation also noted that the throttle control was slightly more difficult to move than usual, which may have prevented the pilot from fully reducing the engine to idle during the flare.
Environmental conditions at the time included a very high ambient temperature of 35°C and a dry, dusty runway surface. The investigation also looked into the airfield's configuration, noting that the runway in use was experiencing a slight negative slope and that the grass was exceptionally short and dry due to a period of drought.
Findings
- The primary cause of the accident was the delayed decision to initiate a go-around following the aircraft's float during the flare.
- The aircraft's float was likely caused by the engine throttle not being fully set to the idle position.
- The examiner's decision to attempt to stop the aircraft rather than executing an earlier go-around created an undesired aircraft state with reduced safety margins.
- High ambient temperatures may have negatively impacted the attention spans of both the pilot and the examiner.
- The dry, hard runway surface and the slight downslope of the runway contributed to reduced braking efficiency.