Recommendation Date
Recipient Name
NZ Gliding Assn.
Text
Consider introducing a procedure whereby the ground-crew check with the pilot that a glider's airbrakes are locked prior to attaching the cable.
Reply Text
The accident sequence could have been broken at a number of points. However, modern, high aspect ratio gliders, capable of carrying large volumes of water ballast, are susceptible to dropping a wing during the initial part of the ground roll. This in turn leads to ground loops which may, themselves, result in damage to the glider.
The reason for the wing drop is a combination of the low speed achieved by the wing runner and the relative ineffectiveness of the ailerons at that low speed.
Overseas it has been found that starting the take off run with the airbrakes EXTENDED assists in wing control during the initial stage of the take-off run. This appears to be because only the outer part of the wing is producing lift and this means that the aileron is producing, proportionately, more lift. The brakes are closed as the aircraft gains flying speed.
This method is effective in preventing wing drop.
Because this is an effective measure we cannot condone a procedure that required the ground-crew to require the airbrakes to be locked before the attachment of the tow rope. However; we do note the pilot's intention to use this control during the launch should have been briefed to the ground-crew and the tow pilot.
The reason for the wing drop is a combination of the low speed achieved by the wing runner and the relative ineffectiveness of the ailerons at that low speed.
Overseas it has been found that starting the take off run with the airbrakes EXTENDED assists in wing control during the initial stage of the take-off run. This appears to be because only the outer part of the wing is producing lift and this means that the aileron is producing, proportionately, more lift. The brakes are closed as the aircraft gains flying speed.
This method is effective in preventing wing drop.
Because this is an effective measure we cannot condone a procedure that required the ground-crew to require the airbrakes to be locked before the attachment of the tow rope. However; we do note the pilot's intention to use this control during the launch should have been briefed to the ground-crew and the tow pilot.
Related Investigation(s)