Alan wrote:
Likewise, the
closure rate would have limited the time that the Hawker crew had to
detect the glider, and the slim design of the glider would have made
it difficult for the Hawker crew to see it.


Am I the only one to question this? If the glider was in a 30 degree
left banked spiraling climb, we should be able to predict where it was
for several minutes prior to the collision --- it was spiraling in the
thermal, moving upwards. His nominal thermal airspeed can be looked up
for the model of glider; the actual value, and the rate of climb can
be determined from the glider pilot.

Since the jet was flying in a straight line (rate of descent, if any
can be found from radar data), it should be fairly easy to figure where
the glider was in the field of view of the jet pilots. As the glider
was probably moving about 50 kt, and the jet was reported at 300 kt, the
glider would have been within no more than about 9 degrees from directly
ahead of the jet.

The glider didn't jump in front of the jet.

I guess the NTSB did not want to do this calculation.

Lets cut the NTSB (and the Hawker pilots) some slack: sometimes *I*
can't spot a glider that is only a mile or two away, even though we're
talking to each other, and sometimes, he doesn't see me either! And we
aren't closing at 300 knots, maybe not closing at all.

It's not just gliders, but the small GA aircraft, too. I'm much more
aware of this since I got a Zaon MRX, because I sometimes get an alert
but still don't find the airplane.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org