What happened
On July 17, 2015, at approximately 18:20, a Cessna 172S, registration TF-FTM, was performing a solo instructional flight at Sandskeið airfield. The student pilot, having recently received solo endorsement, was conducting maneuvers including slow flight and stall entries. Upon approaching runway 15, the pilot encountered significant wind conditions, with the windsock appearing nearly full.
During the landing phase, the pilot utilized 30° of flaps and touched down slightly left of the runway centerline. While attempting to maintain control, the aircraft's left wing lifted, causing the plane to veer left and run on two wheels. Fearing a capsize, the pilot refrained from further braking. The aircraft subsequently veered off the runway, where the nose wheel dug into the soft soil, causing the aircraft to pitch forward and capsize. The aircraft sustained total loss (destroyed), while the pilot sustained minor injuries during the evacuation.
The investigation
The RNSA investigation established that at the time of the accident, wind speeds were 9 m/s (17.5 knots) with gusts up to 14 m/s (27 knots) from a direction of 007°. This resulted in a calculated crosswind component of 21 knots, which significantly exceeded the Cessna 172S demonstrated maximum crosswind limit of 15 knots.
Investigators found that the pilot's control inputs were incorrect for the wind direction. Specifically, the pilot applied left aileron and back elevator; however, with the wind hitting the left side from behind, the correct procedure required left aileron down and elevator down. Additionally, while the pilot and instructor had reviewed the weight and balance and flight plan, they had only checked weather reports for Reykjavík Airport, which showed much calmer conditions.
Findings
- The primary cause of the accident was the underestimation of the crosswind strength and direction.
- The student pilot's lack of experience and incorrect application of flight controls relative to the wind direction contributed to the loss of control.
- The instructor's failure to verify the specific weather conditions at Sandskeið prior to the flight was a contributing factor.
- The soft soil at the edge of the runway caused the nose wheel to dig in, leading to the final capsize.