What happened
On May 11, 2015, a private pilot operating a Jodel D117A, registration TF-REX, departed from Mosfellsbær airfield for a flight over South Iceland. After takeoff, the pilot decided to perform several touch-and-go landings at the same airfield. Instead of following a standard traffic pattern, the pilot turned back toward the airfield to land against the takeoff direction.
After climbing to an altitude of approximately 400–500 feet, the pilot applied the engine mixture control to reduce power and initiated a turn toward the airfield. During this maneuver, the pilot deployed the aircraft's airbrakes to descend. The pilot noted that the aircraft began descending more rapidly than anticipated and responded by applying full power and forward elevator input. This maneuver caused the aircraft to enter a spin, which continued until the aircraft impacted the sea west of Tungubakkar. The pilot sustained significant injuries, but was able to exit the wreckage and reach land. The aircraft was destroyed.
The investigation
The RNSA investigation examined the aircraft's weight, performance, and the flight conditions. While a manufacturer's manual was unavailable, type certification data from the state of manufacture provided critical performance limits. The investigation confirmed that the aircraft's maximum takeoff weight was 617 kg and that the aircraft was within weight limits for the flight.
Data from the type certification also established the aircraft's stall speeds: 55 km/h in level flight, 60 km/h in a 30° bank, and 70 km/h in a 60° bank. Upon inspection of the wreckage, investigators found that the airbrakes were in the deployed position. The investigation also noted discrepancies between the pilot's personal estimates of stall speed and maximum weight and the official certification data.