At the FT get-together in San Diego this past July we had some interesting views "behind the scenes." One was a meeting with the noise abatement folks. They showed us computer plots of the actual paths taken by several hundred flights in and out of SAN, as tracked by ground radar. Most followed the same few standard paths from the final approach fix, but there was a good deal of deviation around the centerline.

The fellow doing the presentation commented that the spread is shrinking with use of GPS. That, in turn, is leading to more noise complaints from residents directly under the center of the path. In the past, normal navigational variation kept planes somewhat spread out even if they were theoretically on the same approach path. Now they all come right down the middle - good news for folks who live a bit to the side, but pity those who get every one right overhead now!

SAN takeoffs and landings are more standardized than most others since it has just one runway (it's the world's busiest single-runway airport), winds (off the ocean) are more consistent than in most other places, and the hills directly inland from the airport constrain the flight paths. The same concepts probably apply elsewhere too, though.