What happened
On April 6, 2015, a Grob G 103 C TWIN III SL motor glider, registration SE-UPT, was conducting a student trial lesson over the frozen Paittasjärvi lake near Pirttivuopio, Sweden. The flight, operated by Segelflygklubben Kiruna, began with a tow to 800 meters. Upon encountering mountain waves, the aircraft climbed to an altitude of 2,400 meters.
During the flight, the pilot attempted to maneuver away from approaching clouds. In the process, the aircraft entered a cloud layer, resulting in a loss of visual references. The aircraft subsequently entered an uncontrolled descent, causing the airspeed to accelerate rapidly. As the speed exceeded the structural limits of the aircraft—surpassing the maximum allowable speed of 248 km/le—the pilot deployed the air brakes. This deployment caused the wings to break apart under the high G-loads.
The instructor ordered the student to bail out and exited the aircraft himself. While the instructor survived with minor injuries, the student remained in the aircraft and was killed in the impact.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the aircraft wreckage, meteorological data, and flight recorders. The investigation reviewed the pilot's training level, the aircraft's maintenance history, and the effectiveness of the emergency response. Investigators also analyzed the cockpit procedures regarding the deployment of air brakes and the student's ability to utilize the emergency exit during the rapid structural failure.
Findings
- The pilot entered involuntary instrument meteorological conditions (IMC) while attempting to avoid clouds.
- The aircraft experienced a rapid increase in speed that exceeded the maximum design speed of 248 km/h.
- The deployment of air brakes at excessive airspeed caused the structural failure of the wings.
- The instructor's training level for this specific flight type was insufficient for the complexity of the flying conditions.
- The student had almost no opportunity to successfully deploy a parachute due to the extreme speed of the event.
Safety action
- The instructor lacked specific training for recovery procedures when visual references are lost.
- The instructional environment may have overtaxed the instructor's cognitive capacity, preventing timely recognition of the risk posed by the nearby cloud base.