The images below were cropped from a plot of KPHX arrival tracks, both before NextGen and after NextGen implementation. The more dispersed purple tracks are from before last September 18th (pre-NextGen). The more concentrated blue tracks are from after last September 18th (new NextGen tracks).
Northside Arrivals to KPHX, in an East Flow
This image provides a very clear example of focused noise impact due to route concentration. In the image above, the approximately 4-mile tall orange rectangle shows the broad dispersal of pre-NextGen arrival flight paths (purple tracks). With NextGen (blue tracks), nearly all of these flights are now pinched into a thin westbound downwind leg, marked with the short orange rectangle (roughly 1/4-mile tall). This shows an enormous noise impact on residents below, midway between Indian School Road and Northern Avenue.
This image also clearly shows the remaining duty of the radar controller: to issue approach clearances (and thus initiate the left turns off the westbound downwind leg). The green rectangle shows where turns are initiated, primarily between N 45th Avenue and N 91st Avenue, once ATC sees that a turn will maintain a steady and conflict-free arrival flow to the three KPHX runways.
Southside Arrivals to KPHX, in an East Flow
This image shows two NextGen changes: a pronounced concentration of tracks, and a clear shift to the west. Note the purple tracks were dispersed over a 5-mile wide corridor. Note, too, the core of the arrival track (heavy purple and heavy blue areas) shows a shift approximately 4-miles to the west. The purpose of this shift is to enable earlier turnouts on KPHX departures taking off to the east and heading west to KLAX, KSAN, and the Pacific Ocean.
KPHX Final Approach Course, in an East Flow
This image shows that, generally, there is no substantial NextGen change in the final approach course (area immediately west of the KPHX runways) in an east flow. Feeds off the base legs and downwind legs continue to be widely dispersed, and the straight-in arrivals (form KLAX, etc.) are slightly more precisely concentrated.
Departures from KPHX, in a West Flow
This image shows the intensity of flight track concentration for NextGen departures. Notice how the purple tracks are dispersed. Then, notice how this has been reduced to three narrow corridors, averaging less than 1/2-mile in width.
Northside Departures from KPHX, in a West Flow
This image shows the intense route concentration over the Grand Avenue area. Notice the wide dispersal of departure flight tracks prior to NextGen; the purple lines fill most of the image, so that all residents share a relatively equal burden of KPHX noise impact. This was drastically changed by NextGen. Not just by focused departure streams, but also by focused arrival streams.
The orange ellipse shows an area of essentially non-stop noise impact. The red line depicts arrivals in an east flow. Where the red line crosses the heavy blue line, Phoenix residents now must endure focused air traffic streams for both west flow departures and east flow arrivals.
Southside Departures from KPHX, in a West Flow
Within this image, the orange rectangles show the concentrated noise impact; departures dispersed over nearly 6-miles become focused within barely a half mile corridor. The green rectangle shows where ATC is issuing turn clearances (typically, direct to some distant fix), once the departures are south of the arrival stream above.
This image also shows the amplified noise impact where NextGen arrival tracks cross NextGen departure tracks. The red line approximates the NextGen arrival stream from the south side. The red ellipse marks an area with intense noise impact due to NextGen changes. Note that where the red line crosses the heavy blue line, residents experience full-time noise impacts, from both west flow departures and east flow arrivals.
- Phoenix City Council Looks For Options In Flight Path Dispute — 4/16/2015 article by Alexandra Olgin, at KJZZ.org.