Gremline Flight Safety Report: Wing Drop During Glider Launch / Gremline Safety Quiz

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Wing Drop During Glider Launch

A Schleicher ASW 20L glider suffered a right wing drop as it became airborne during a winch launch. The glider yawed and then rolled uncontrollably to the right. The winch cable was not released by the pilot and the glider rolled inverted and struck the ground. The pilot suffered severe head injuries and died four days later.


 

The surface wind at the time of launch was 115/10kt giving a crosswind component of 3kt, well below the aircraft crosswind limitation of 13.5kt. Full cable release checks were conducted prior to beginning the launch and the cable release operated correctly during these checks. The winch launch was conducted normally with the assistance of a wing walker to hold the wings level until the pilot was able to do so using aerodynamic controls. The first launch attempt was aborted when the glider overran the winch cable. The winch cable was reattached with the glider at the position where it had come to rest, some 50m ahead of the original start point. During the second launch attempt the wing walker had to push downward on the left wing to keep the wings level. He continued to do so until he could no longer keep pace with the accelerating glider. The glider became airborne almost immediately and rolled to the right. The right wingtip struck soft ground causing the glider to yaw and roll rapidly to the right, pitch nose down and somersault inverted. The tail broke off causing the top of the canopy to bear most of the impact. The pilot, who was restrained by a four-point harness, suffered severe injuries to his unprotected head.

      The winch driver stated that the glider appeared to drop its right wing as it became airborne. In accordance with his training he maintained power to continue the launch until the glider reached 90 degrees bank and the nose began to drop. He then cut power and applied the winch brake. The cable remained attached to the glider throughout the accident sequence. There was no evidence that the winch or its operation had any adverse effect on this launch.
      The cockpit cable release control of the Schleicher ASW 20L is situated to the left of the aircraft centreline low down at the base of the instrument panel and just ahead of the base of the control column. An identical control to allow rudder pedal adjustment is mounted just to the right of the cable release. The cable release terminates in a spherical yellow knob about 30mm in diameter. The rudder adjustment knob is identical in size, but coloured brown.
There was no evidence of any pre-impact failure to any of the controls or of the airframe. An imprint on the upper wing skin from part of the right aileron bellcrank that probably occurred during impact indicated that there was a right aileron deflection of 15 to 27 degrees trailing edge down at impact. Full aileron deflection was measured at 31 degrees trailing edge down. The cable release mechanism was examined and found to operate normally.

 

 

BGA Guidance

The issue of wing drop during launch is the subject of guidance produced by the British Gliding Association (BGA) and discussed in several articles published in UK gliding magazines. The consensus is that even gentle contact of the wingtip with the ground can result in considerable yaw leading very quickly to unrecoverable rates of roll. Pilots are taught to release the cable immediately a wingtip makes even slight contact with the ground. The BGA Instructors manual contains the following guidance:


”Release the cable immediately if a wing goes down or anything else goes wrong during the ground run, e.g. an overrun. Keep the left hand near to the release knob, or, depending on its position – for example if applying left aileron will make it awkward to reach – actually take hold of it.”

The BGA leaflet ‘Safe Winch Launching’ includes:


”The demonstration might include patter such as the following:
* As the cable tightens, ensure your left hand is close to, or on the release.
* As the glider moves forward, keep the wings level using the ailerons. Large deflections may be needed initially.
* If a wing goes down, release.”


The control ergonomics of the accident aircraft may have made it difficult, or impossible, for the pilot to get his left hand to the cable release knob and to operate it immediately while he had the control column deflected far to the left of the cockpit to counteract the initial right roll. The initial right roll, and the fact that the wing walker had to hold the left wing down at the start of the launch, may indicate that the pilot had inadvertently applied right roll control at the start of the launch.
      The BGA sent all gliding clubs a revised edition of the “Safe Winch Launching” leaflet that all glider pilots and those responsible for safe operations should read again to refresh their memory. The BGA also sent a letter to all BGA gliding instructors that included the following advice:


”There is inevitably a healthy level of debate on winch launching techniques which should be encouraged to aid better understanding of what is a complex task. One point that really does need to be emphasised however is the need for the pilot to keep his/her left hand firmly on the release during the initial part of the launch.”

 

The gliding club where this particular fatal accident occurred conducted a trial in which the person assisting the launch (usually the wing walker) will, after connecting the cable, look inside the cockpit to see if the pilot’s hand is on the cable release. If not the assistant will remind the pilot to do so.

 


In my experience there are two types of lead-in to an accident. One is where things gradually go wrong and a chain of minor incidents is allowed to develop until the whole thing is out of control and an accident happens. Another lead-in is where things go disastrously wrong in a very few seconds and unless you are fully prepared and have planned and practised your immediate action you may well become another statistic. I have Martin-Baker to thank for saving my life in one of the latter situations. You don’t have the option in a glider of pulling a handle and leaving the scene in a rapid vertical direction so you must prepare for what can go wrong.
      A winch launch can very quickly go wrong. Give yourself a chance by deciding on your immediate actions and following them on each and every winch launch.
      The facts relating to this accident are taken from AAIB Field Investigation reference EW/C2006/09/06 which source is gratefully acknowledged. Any conclusions and comments are those of the Gremline Managing Editor and do not seek to reflect AAIB or BGA views.

 

 

Traps for Beginners — And Experienced Pilots, Too!

A Few Samples from an Endless List.

 

Take our safety test. Add up the number of statements you have used at one time or another. Be honest. Check your score at the end of the test.

 

” I took off from this strip yesterday, without any problem.”
” The plane was perfectly serviceable yesterday.”
” The cloud will lift once I get past these hills.”

“ There’s plenty of fuel on board. I’ve only done a couple of short trips since refuelling.”
” A couple of small children in the back won’t make much difference.”
” I’ll have that checked next time I see an engineer.”
” Fred said it’s OK and he’s an experienced pilot.”
” It’ll save time if I take off from the intersection.
” I should get there before dark.”
” The fuel sample is perfectly clear so that’s OK.”
” I can sort the speed out before touchdown.”
” That sounds different – probably my imagination.”
” It doesn’t really matter all that much.”
” I’ll connect jump leads and the battery will charge as we go along.”
” That must be that disused airfield near Bedford.”
” I can always climb above the cloud.”
” I can’t be off track already.”
” It’s up to the engineer to check the tyre pressures.”

“ I don’t need to check the ident every time.”
” Why doesn’t that idiot stop talking on this frequency?”

“ I don’t need to be checked by an instructor.”
” I just managed to scrape in before it clamped.”
” I can’t be bothered with all that stuff.”
” Fred said he has rolled one of these. I’ll give it a try.”
” Acceleration’s a bit slow but I can make it.”
” I can get onto the runway before that clown.”

“ I have the right of way.”
” I’ll show you some really low flying.”

“ Come on! Come on! I haven’t got all day.”
” You jump in and start the checks. I’ll be there in a minute.”
” All this paperwork is a load of rubbish.”
” I’ll sort it out once we are airborne.”
” I’m late so we will debrief your lesson tomorrow.”

If your score is one or more, you’ve failed!

 

 

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Text and Photographs © 2009 Gremline & Hill House Publications, unless otherwise stated.

 

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