On Thursday, June 20, 2013 3:25:18 PM UTC-6, JohnDeRosa wrote:
Sad event.



The most telling statement seems to be the very last line of the report.



"The tow rope broke during the initial takeoff..."



I take this statement at face value. The rope BROKE. It didn't otherwise inadvertently release such as a back release, the release was mistakenly pulled or failed, etc.



Never having done an auto or winch tow, is it unrecoverable if the rope would separate from the glider at 200ft when at a "steep nose-high attitude"?



- John

The answer also depends on airspeed and how quickly the pilot initiates a recovery.

There's an envelope from within which a safe recovery is possible. I call it the "AAA envelope" bounded Altitude, Airspeed and Attitude. With enough airspeed and altitude, you can recover from anything. A steep nose-up attitude at low altitude and airspeed can be unrecoverable.

This can actually be computed using physics simulators like Matlab. For example, from the initiation of recovery, an ASK-21 at 60kts, which is a typical winch airspeed, and 45 degrees nose-up can recover to a normal glide at 1.3xVs with no loss of height assuming a well trained pilot using an aggressive recovery technique. OTOH, an ASK-21 at 50 knots and 50 degrees nose-up will lose 65 - 75 feet so you need to be higher than that. Common sense says you need to add a 100% safety margin on top of this.

Winch launch training involves a lot of these recoveries. A pilot on ground launch should be trained to expect a launch failure on every launch at any altitude and be prepared to deal with it safely.

Continuing the scenario a bit, there's obviously a point defined by height and distance remaining where landing ahead on the runway is no longer possible. If you're too close to the end to land and and too low to circle back, you're in what's been called the "end trap". Auto towing with a short tow rope it's easy to get "end trapped" which I suspect in this accident. With winch launch, you reach a height where a short pattern is possible before the land-ahead option is lost.