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Deutscher Hängegleiterverband e.V.

DHV
26.07.2012

Warning: fatal accident – spiral dive on Swing Mistral 6

A 47 year old pilot had a fatal accident after impacting while in a spiral dive at the Kandel landing field on 23.6.2012. According to GPS recordings and eye witness accounts, the pilot began the spiral dive with the Swing Mistral 6 at 250 meters over ground height. The pilot had many years of flying experience. According to accounts from fellow pilots, the deceased did not have much spiral dive experience and had not flown a spiral dive before on the Swing Mistral 6. The pilot was familiar with theoretical procedures for performing the maneuver on a Mistral 6, and also familiar with the fatal DHV accident report due to a spiral dive on a Mistral 6 in 2011.
A detailed accident report (in German) can be found here.
Swing Mistral 6 paragliders were tested and certified by the LBA recognized DHV testing center in April 2010. The manager of the testing center noted: “During test flights it has been determined that recovery characteristics from a spiral dive are at the upper limit of the B class. When the test procedures set down by  EN 926-2:2005 and LTF 09 are followed exactly, then the glider reacts in accordance with a B class rating (see also the video documentation). The manufacturer has been instructed to describe spiral dive behavior at sink velocities greater than 14 m/s and how to recover from this maneuver.” The handbook for the Mistral 6 contains appropriate information for spiral dives. All DHV test reports for the Mistral 6 also contain a corresponding safety note: “At sink velocities >14m/s active recovery by the pilot may be necessary to exit from a spiral dive (see handbook)”.

Data logger tests conducted on the Swing Mistral 6 and publicized in DHV-Info 174 indicated that at sink velocities greater than the LTF 14 m/s requirement, the glider has a severely delayed self recovery. At sink velocities greater than 18 m/s, the glider enters a stable spiral dive which needs an active recovery from the pilot (strong symmetric brake input).

As a result of the fatal accident with a Mistral 6 in August 2011, the DHV made strong recommendations to the EN working group for testing Norms to revise and increase safety margins for the spiral dive test. The revisions were agreed upon in July 2012 and the new criteria will be used by the DHV in all future LTF tests.

Warning to all pilots: Spiral dive maneuvers should always be performed that on recovery at least 250 meters height over ground remain. Low-airtime or inexperienced pilots should carefully study current training material before attempting spiral dives – or should avoid this maneuver completely. At high sink velocities, releasing the inner brake to start recovery may cause the glider to further accelerate. To control sink velocities and conduct controlled recoveries it is of utmost importance that the outer brake is also used. Practice of the maneuver during the course of a recognized SIV training is strongly recommended. Under Safety on www.dhv.de we have published a number of articles on this theme.
Pilots of the paraglider Swing Mistral 6 must carefully study and abide by the recommendations to spiral dives in the manufacturers handbook.

Swing Paragliders have made the following comments to the accident and on the behavior of the Mistral 6 in a spiral dive.