ANALYSIS: NextGen Early Turns by Dash-8’s in Seattle

The new NextGen routes implemented for the SeaTac Airport [KSEA] follow the same general pattern we have seen at other NextGen-impacted airports like LaGuardia, Charlotte and Phoenix: FAA’s goal is to help the airlines maximize profits by shortening engine usage as much as possible. This is done in three ways:

  1. maximize ‘runway throughput’ by implementing immediate turns on departure, so that if a hub airline sends ten planes to the runway all at the same time, the total time spent waiting for others to takeoff will be minimized.
  2. minimize distance flown by making the overall route from departure airport to destination airport as direct as possible.
  3. shorten the final approach by bringing the flight in lower and with turns closer to the landing runway.

The net effect is a compacted airport traffic pattern, with both departures and arrivals tightly concentrated onto narrow and more impactful NextGen routes, which have been precisely defined for automated flight. So, people who previously heard just an occasional flight now hear a nearly nonstop stream; one after another after another, not unlike the ‘drip-drip-drip’ of a water drop torture.

In Seattle, an enormous number of flights are conducted using Dash-8 turboprops, mostly flown by Horizon, as a feeder for Alaska. Under NextGen, it is FAA/ATC policy to handle Dash-8 departures differently than the jet flow. Not just during heavy departure pushes (a frequent and common problem at all hub airports), but for ALL Dash-8 departures. In a North Flow, Dash-8’s and other turboprops are flown low and straight-out, over heavily noise-impacted Beacon Hill. And then there are the routinely aggressive early turns, in a North Flow (mostly to Portland, but also to Eugene, Medford, etc.) and in a South Flow (for destinations such as Vancouver, Victoria and Bellingham). The consequence of these early turns is that airport neighbors in residential neighborhoods, thousands of people who would never see overflights at an airport more considerately managed, are woken up before sunrise and kept awake long after sunset. Not just occasionally but every day, 365 days per year. The PDF below offers some graphic examples of the early turn impacts:

This pop-out view is scrollable, and the PDF copy may be downloaded.