On Sunday, October 6, 2013 2:08:30 PM UTC-6, John Galloway wrote:
At 15:34 06 October 2013, Bill D wrote:

On Sunday, October 6, 2013 2:53:16 AM UTC-6, Don

Johnstone wrote:





http://www.aaib.gov.uk/cms_resources.cfm?

file=3D/Schempp-Hirth%20Nimbus-3=

%20glider%20G-EENN%2006-13.pdf



There are so many bonehead screw-up's in this report it

makes one want to

c=

ry.



A few:



1. Not staging the glider so it points exactly at the winch.

2. A VERY long, slow, wobbly takeoff roll despite a 15kt

headwind

component=

..

3. A failure of the launch crew to stop the launch when a wing

went down.

4. Not releasing when it was clear the ground roll wasn't

precisely normal.



A dry Nimbus 3 launching into a 15 knot wind would likely

have aileron

cont=

rol BEFORE the roll began and should have been airborne in

around one

secon=

d after rolling about a glider length. Obvious point: Once

airborne,

there=

's no danger of dragging a wing.



At least you Brits are good at writing accident reports.





This tragic accident happened to one of my club colleagues.

With reference to the comments above:



1) There is nothing in the AAIB report to suggest that the glider

was not pointing at the winch. It was situated 30m from the

position that the cables had been drawn to and so the cable

would have been pulled over to the glider. It may have been

better to point the glider away from the winch and somewhat

towards the line of the cable. (Better still to have minimized

the bow in the cable by positioning the glider closer to the cable

and pulling the cable as straight as possible.)



2)There is nothing in the report to suggest "a very long, slow,

wobbly takeoff roll". I can report from personal experience of

many launches from the winch and professional winch-driver

involved that this is a very powerful rapidly accelerating winch.

The AAIB report makes direct reference to the fact that the

winch was operated correctly according to the manufacturer.

The cable released at 4 seconds from the start of the launch

with the glider already airborne and unrecoverable so that

leaves no time for a takeoff roll as characterised above.



3) There is no suggestion in the AAIB report of a "failure" by the

ground crew to stop the launch. This point is specifically

addressed:



"On this occasion both the wing holder and the launch signaller

saw the wing touch the ground but events then developed

quickly, so it is unlikely that either of them had time to consider

and make a ‘stop’ signal. Therefore, the responsibility to

release the cable would have to rest with the pilot"



4) Agreed - to release the cable as soon as the wing cannot be

kept level is vital.



John Galloway

I'm not basing this entirely on the AAIB report - I can read between the lines and I have other sources. No, the AAIB didn't address those issues although they certainly should have.

Instead, they ignored a wealth of obvious facts and blamed the accident on the release position which has worked just fine in literally millions of releases. Even so, if the owner, or a maintenance shop, thought there was a problem, adding a flexible release extension is SOP. Such an extension is even shown in Figure 5 with the release T-handle BEHIND the stick. Figure 6 showing a 'pilot' with his RIGHT hand blocked from reaching a release is grossly misleading. I hope the AAIB doesn't risk its reputation by presenting this argument in court.

Independent sources the glider was not pointing at the winch and, John, even you suggest that's acceptable. I say the rope must be dead straight and the glider pointed exactly at the winch - no exceptions. This accident is a great example of why.

I've been officially involved in very similar accidents where the launch crew had far less time yet DID stop a launch in time to save a pilot who failed to release. Your crew had plenty of time to stop the launch. If the signaling system didn't permit such a timely signal, that's yet another problem that needs to be addressed.

Clearly the acceleration was VERY slow and the wing did drag so the roll was wobbly. Rolling 29m (95 feet) into a 15 knot headwind component proves it. A dry N3 with flaps set for winch launch lifts off below 33 knots so with the headwind, the winch only had to add 18 knots which requires less than one G for less than one second over a distance of less than 20 feet.

All winches, even a Skylaunch, have throttles so the phrase "very powerful rapidly accelerating winch" is meaningless. Acceleration depends only on the throttle setting.

So, what could have prevented this accident?
In order of importance:

1. Faster acceleration. Get a glider airborne and climbing before a wing can drop.

2. Insist every launch have the rope exactly straight and the glider pointed exactly at the winch.

3. Better communications. Maybe someone at the launch point should have a thumb hovering over a button that lights a big, bright "EMERGENCY STOP" sign in the winch cab. Better yet, have that button trigger the guillotine.

This accident report will serve as a classroom example for many years including a "can you find the screw-ups?" exercise. If you suspended the Imperial arrogance long enough, you might hear the groans and forehead slapping from the Continent and around the world - and if you listened to what they're saying you might start improving your miserable accident record.