L2012-06 Glider accident at Rautavaara aerodrome on 3 July 2012

An accident happened at Rautavaara aerodrome on 3 July 2012 at 12:16 local time in the takeoff phase of a glider winch launch. A Grob Astir CS single seat glider, registration OH-658, collided with the ground and was completely destroyed. The pilot of the glider sustained serious injuries.

The pilot intended to fly a training flight at Rautavaara aerodrome. Good gliding weather conditions prevailed and the flight in question was the fourth glider winch launch on the occurrence day. According to the established practice, winch launching activity took place in an area which was to the west of the paved north-south main runway. Tall hay, approximately 60-70 cm high in places, grew in that area.

During the take-off run the glider’s right wingtip touched the ground twice in rapid succession. Very soon after this the glider lifted off in a non-stabilised flight condition, turning hard to the right and becoming nearly inverted at the height of approximately 10 m. The pilot did not have the time to release the towing cable. The winch operator noticed that the glider was in an abnormal position and aborted the launch at which time the cable came loose from the glider. Once the pull of the cable subsided the OH-658 collided with the ground, nose first in a nearly inverted position. From the point of impact the glider bounced to the right and continued to slide on its back for approximately 14 m. The glider came to a full stop at 86 m from the point of takeoff. The OH-658 had no technical fault prior to the accident.

The direct cause of the accident was that the right wing dropped during the takeoff phase’s ground run, which resulted in the wingtip hitting the tall hay and, ultimately, the ground. This caused strong drag on the right wing, making the glider turn to the right. As the winching continued the glider lifted off at a steep angle of climb, at which time the pilot lost control of the aircraft.

A contributing factor was the decision to continue flight operations in an area where tall hay grew.

Safety Investigation Authority, Finland issued a safety recommendation to the Finnish Aeronautical Association, proposing an update to the ‘Winch Launching; Flying, Training and Operating Instructions Guidebook’ as regards the section that deals with emergencies during the ground run phase of glider winch launching. In addition, it is recommended that the guidebook be distributed to student glider pilots as part of their training material.

Safety Investigation Authority, Finland issued a safety recommendation to the Finnish Transport Safety Agency, proposing Aviation Regulations AGA M1-1 and OPS M1-6 to be revised so as to eliminate any inconsistencies in their respective aerodrome classifications.

L2012-06 Report (pdf, 0.5 Mt)