The problem mentioned below is not confined to the wind SPEED calculation.
Some months ago I flew a fairly straight ridge at 80 kts for many miles,
with the SN10 telling me that the wind was straight along the ridge. I knew
the calculated wind angle could not possibly be correct, because if it had
been, there would have been no ridge lift to keep me airborne, nor would I
have tracked along the ridge with the big crab angle between the ridge and
the nose of the sailplane that was clearly visible outside the canopy.
Eventually I made a couple of circles, after which the SN10 gave me a much
more sensible wind result.
Ray

"Doug Haluza" wrote in message
ups.com...
No, the ILEC SN-10 cannot compute winds in straight/level flight. In
fact, there is a known problem when flying long straight runs in ridge
lift, where the wind speed drifts up to unreasonable values (like as
much as double the true speed). It also tends to hold on to a higher
wind speed when the wind dimishes. This can be big trouble when flying
along a ridge into a becalmed area. When you turn around and then
towards your field to land, the wind display updates, but by then it's
too late.

This is not a software bug per se, it is just a limitation of using GPS
and airspeed to measure wind without a heading sensor. Adding a
magnetic heading sensor won't really help, because the heading error is
similar to the crab angle. So without a lot of calibration, you won't
see much benefit, and you just introduce the possibility of greater
error. A two antenna GPS would be a good solution, but the current
consumer products are intended for marine applications, and are not set
up to handle high bank angles.