unusual overhead occurence while on family walk.while on a family walk with our two dogs,my family and I walked along a road that is is under one of the approach flight-paths used by nashville int. airport. This road is remarkable for the fact that it is in a neighborhood that was depopulated as the airport grew.The road is closed to thru traffic and blocked, although accessable on foot.It was dark and we carried a flashlight. No one that we knew of was on the road.We were able to see and hear the approach of about three passenger jet planes as we walked. Each plane was clearly visible and fairly well into descent as we saw them. There were distinct intervals of time between each air approach when the windless quiet of the night resumed. In other words the traffic wasnt "stacked up". It was during one of these interludes that everyone in the family heard the sound of something up above us.The sound was of something clearly moving thru the air,BUT!!! there were no lights no engine or jet sounds... nothing but this sound. I want to emphasize that there was no natural wind activity in the area. Everyone was perplexed and at a lost for explanation. There were two events of this nature. At the end of this section of road an airport police squad car was parked.We are wondering if anything like this has ever been reported. We are stumped. We know all of the noises and effects associated with planes overhead in this area,as we have walked it before.((NUFORC RESPONSE TO WITNESS))Dear Mr. ((name deleted)), Thank you very much for the report! Yes, what you report has been reported to us before...I believe you heard the turbulent vortex activity generated by the tip of an airplane wing. When airliners land, using a relatively high angle of attack on approach, the air on the bottom of the wing "leaks" around the tip of the wing. This continuous process generates a "tornado" at the tip of the wing, which persists in the atmosphere for a long period of time. The twisting air can be heard at ground level, and it is quite prominent in a calm sky. That is only a theory, but I suspect that if you return to the same location, you can experience the same effect. Thank you for sharing the information with our Center! Cordially, Peter Davenport--Peter B. Davenport, DirectorNational UFO Reporting Center P. O. Box 45623 University Station Seattle, WA 98145E-Mail: [email protected]: www.UFOCENTER.comReporting Hotline: (206) 722-3000 \((END RESPONSE))