Its interestign to think that had the world not progressed beyond the turbo prop with the development of big fan jets just how much vibration noise we would suffer in locations like mine where I am pretty much underneath east west and north south airways.
i wouldnt mind as I love the turbo props distinctive drone but others.......
Again Dave R thanks for the info, if they were in Nevada probably routed back via Bermuda and or Azores and that would account for the track up from the SW quite nicely too.
I lived in Bermuda for a number of years and as well as being home to a squadron of P3s it had a couple of spooky USN C130s which i think maintained VLF radio contact with submerged boomer subs so the sound of four Allison TPs was a common one. Also a lot of C130s staged through there en route from the Lockheed facility in Georgia back to their homes with European and mid east airforces , just about every AF worth the name has Hercs except of course for the old Soviet bloc so there was often something interesting to see in transit since Kindley Field was very much a staging post for Atlantic ferries of all types.