On Mon, 07 Jun 2004 20:33:30 GMT, "Jay Honeck"
wrote:

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

We've heard it, too. Only the big jets seem to make that noise.

It's very cool, almost creepy.

My vote?

It's got something to do with air building up in front of those large
cowling/nacelle inlets while the jets "glide" towards the airport
at flight-idle.

When the power comes back up, the aerodynamics in front
of the cowling(s) changes and the result is the sound you hear.

(that's my WAG anyway....).

Bela P. Havasreti