Yeah, I can't believe we didn't hit a few Joshua trees.

I just had a thought...I suspect it is very difficult to measure very low airspeeds with sonar. For example, if you are trying to measure 5 mph at a temp where the speed of sound is 750 mph, you would have to be able to know the speed of sound very accurately in addition to being able to record the sound pulse time very accuratley since 5 is only about 0.67% of 750. This sounds expensive.