It may be the thrust reversing. I presume that the sound is very much
louder on cool humid nights. I lived south of Willow Run (YIP) for many
years, but on those humid nights I could even hear the jets from Detroit
metro (DTW?) which was much further away.

It could also be the sound echo off the steep sides of those rugged hills,
eh?


"gatt" wrote in message
...

If you stand a quarter of a mile or so from the threshold at PDX 28R, (or
at
the cemetery at McCarran in Las Vegas, the incoming), you hear a windy,
howling sound that is so well defined it seems to take shape in the sky
after the larger jets have passed for touchdown.

Has anybody heard it? What is that? Our theory has always been that its
the wingtip vortices collapsing.

-c