On 06/20/2013 09:53 PM, Steve Leonard wrote:

http://www.ntsb.gov/aviationquery/br...FA010 &akey=1

Happened to be looking through the NTSB Database and saw that they updated the report about a month ago.


Firstly let me express my condolences to the friends and family of the
late pilot. There has been a lot of noise on this thread about this
accident. But adding to the above with the additional documents and
video published he

http://dms.ntsb.gov/pubdms/search/hi...KEN=7351 7888

I would like to post this in the spirit of learning from past mistakes.
I think this is what probably happened:

- The length of the tow rope was much shorter than the typical minimum
length of 300m used for a conventional auto tow launches. The runway was
also shorter than that which would normally be considered suitable for
auto tow. Thus this operation should be regarded as a stunt contrived
for the benefit of the camera's rather than a conventional soaring launch.

- The video shows the glider being towed horizontally behind the tow
vehicle and then performing a "kite" manoeuvre where the glider pitches
nose up, gains altitude rapidly and accelerates due to the geometry of
changing the relative direction. Intentional "kite" manoeuvres are
conducted in a controlled manner during a conventional ground launch.
They can also occur unintentionally during aerotow where they can cause
tug upset accidents. It is not clear if the kite manoeuvre on the crash
flight was initiated deliberately by the pilot for the purposes of the
camera, or if it happened accidentally.

- In the accident flight the kite manoeuvre caused the rope to break.
The pilot then lowered the nose to return to a normal gliding attitude.
(Even if the rope did not break, the short length of the rope would have
required the manoeuvre to end within a few seconds, eg by a back
release, the pilot releasing or the pilot lowering the nose.)

- As the launch was conducted outside of the parameters of a normal auto
tow, there may have been insufficient runway length available to land
ahead - the conventional recovery procedure for a ground launch failure
at this hight. The tow vehicle also presented an obstacle to landing
ahead, another aspect which differs from a conventional auto tow launch.

- Rather the pilot attempted a 180 degree turn to land downwind on the
runway again, similar to the recovery manoeuvre from an aerotow rope
failure at that altitude. However the pilot lost control, stalled and/or
spun and crashed.

- It is standard procedure when recovering from a ground launch rope
failure to lower the nose and the WAIT UNTIL AIRSPEED RECOVERS BEFORE
TURNING OR USING AIRBRAKES. As the glider experiences lowered or
negative G during the "push over" manoeuvre used to lower the nose after
the cable brake, it can fly normally even if the airspeed drops below
the nominal stalling speed. However after the push over is completed,
the glider experiences 1G and requires airspeed above nominal stall
speed to fly. This may be achieved only after some seconds after the
nose has been lowered. Any attempt to manoeuvre the glider during this
period can easily lead to loss of control. This is clearly illustrated
in this BGA training material:

http://www.gliding.co.uk/bgainfo/saf...deo/spin-4.mp4

- I suspect the pilot had insufficient airspeed when he attempted the
180 degree turn.

The pilots options in this situation were compromised due to the non
compliance with the norms for an autotow launch. It is not clear whether
he had sufficient altitude, speed and runway space to complete a safe
landing.

I hope that readers will appreciate that ground launching can be
conducted safely, provided that it is conducted within established
norms. Pilots should have appropriate training and ground launch
operations should be conducted under the supervision of skilled and
current ground launch instructors. However deviating these norms can
rapidly increase the potential hazards.


Ian