"Andy" wrote in message
oups.com...
On Apr 11, 5:38 pm, "Kilo Charlie" wrote:

If you had data you would need to careful in its interpretation.
Glider launches usually take place when thermal activity has started.
Wind shear and thermal downdrafts can be expected and, singly or in
combination, and they can easily reduce climb rate to zero or make it
negative.

Let's say the data show you only need 1000 foot of the 5000ft runway
and the predicted climb rate is 200fpm for the first 500ft, and the
predicted thermal strength is 6kts, and the wind is gusty. Would you
launch? I suspect the answer would be yes. We do it all the time and
usually it works out ok.

Since I know what prompted the question I'll comment that Williams has
similar conditions to Flagstaff. That airport has a poor record for
summer takeoff accidents and that's for airplanes without a glider in
tow. Usually it works out ok though.

Andy

So your response seems to be similar to some other local pilots Andy.....the
data is not reliable. Would you then surmise that those Flagstaff accidents
were by pilots that looked in their POH and found that it was incorrect? I
think not. My opinion is that they felt that the data was bogus as well and
went by the "feels right to me" approach ending in disaster.

Casey