posted on May, 2 2014 @ 04:36 PM
a reply to: mindseye1609
It's the Doppler Effect. Once they get in an area where the rotors are pointing away from you somewhat, and there are buildings and trees around, the
sound tends to get blocked, and distorted. I see that a lot with planes going overhead too. The plane will be a few miles ahead of where I'm hearing
the sound, so I'm looking one way and it's already past where I'm looking.
Sometimes they have to visit with the FAA, and other agencies at the airport, so they'll fly in to do their meeting, or whatever. They usually try to
get in where they have the least impact on airport operations, but they usually have to cross the runways, so the tower tries to squeeze them through
arrivals and departures to let them cross over.
If they stay below a certain altitude, then they keep out of the way of other traffic, and it's easier for the controllers to deal with them on the
edit on 5/2/2014 by Zaphod58 because: (no reason given)