In article
Larry Dighera quotes the NTSB report:


Before the
collision, the Hawker had been descending toward RNO on a stable
northwest heading for several miles, and the glider was in a 30 [degree],
left-banked, spiraling climb.

. . .

Because of the lack of radar data for the glider's flight, it was not
possible to determine at which points in each flight each aircraft may
have been in the other's available field of view. Although Federal
Aviation Regulations (FARs) require all pilots to maintain vigilance
to see and avoid other aircraft (this includes pilots of flights
operated under IFR, when visibility permits), a number of factors that
can diminish the effectiveness of the see-and-avoid principle were
evident in this accident. For example, the high-speed closure rate of
the Hawker as it approached the glider would have given the glider
pilot only limited time to see and avoid the jet. 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.

Alan