Quieter skies? Or noisier?

Will new avigational equipment reduce noise from Sea-Tac?  We're skeptical.

The Seattle Times, in a front-page story in its issue for Sunday, 30 August, touted a new avigational system, under consideration for Sea-Tac Airport.  The Times said, "It promises to save airlines big money on fuel while cutting overflights, noise, and carbon emissions for people on the ground."  

The article reports on a recent test flight of an Alaska Airlines airplane equipped with what is called "NextGen" avigational gear.  According to the Times, Alaska Airlines projects reduced overflight noise for 750,000 Seattle-area residents, along with annual savings at the airport of 2.1 million gallons of fuel and 25,000 tons of carbon-dioxide emissions.

The paper quotes the text pilot, Mike Adams, as saying "There is nobody who loses here".

An interesting side note:  Alaska admits that overflight noise affects 750,000 Seattle-area residents.  This is a distinct deviation from the FAA's "party line", which insists that overflight noise only affects a handful of people very very close to Sea-Tac Airport.

On to the main point:  The Times does not explain why this system is projected to reduce arrival delays at Sea-Tac, or elsewhere.  We know, though, that this & other systems based on GPS technology provide much more accurate data as to where a plane is than the present radar-based system.  Knowing where everyone else is allows pilots to fly closer together, & thus more arriving aircraft can be landed in any particular time slot.  The pilots know where they are, they don't have to rely on the air traffic controllers' interpretations of radar -- often obscure.

That sounds good. More plans arriving without more runway construction.  Less reliance on air-traffic control.  Much greater assurance for flight crews as to where they & the other aircraft (& the ground) are.  And, we are told, at a cost of not much more than $1 million per plane.

In the case of the Seattle metropolitan area, it would be possible to design better noise-abatement corridors for arriving aircraft.  The Times ran a map (not shown on the website), with possible corridors for planes arriving from the north.  These planes might come into their landing patterns not up in Snohomish County (as at present) but essentially over downtown.  In other words, over fewer people.  The map suggests that noisy arrivals would not be heard north of, say, the Ship Canal.  Could be.

More importantly, the paper, & Alaska Airlines, are overlooking two vital equations:

(1)  More planes in = More planes out

(2)  More planes = More noise

This will be particularly true for folks under departure overflights (generally regarded as creating more noise for more folks than arrivals).

Areas now receiving more noise from the new third-runway flight patterns would experience even more noise when the NextGen system is deployed.  This is not the same as the Quieter Skies that the Times is promising.

* * * * *

URL for Times story (not a live link -- paste into your browser):

http://seattletimes.nwsource.com/html/businesstechnology/2009772140_seatac30.html