Sunday, January 24, 2010

NextGen Night

This should be quick. I just heard about this while watching the news.

”Due to WEATHER / TSTMS, there is a Traffic Management Program in effect for traffic arriving The William B Hartsfield International Airport, Atlanta, GA (ATL). This is causing some arriving flights to be delayed an average of 4 hours and 46 minutes. To see if you may be affected, select your departure airport and check "Delays by Destination". “

(Emphasis added)

That’s from the FAA’s own web page.

Bear in mind that we’re in the middle of The Great Recession and it’s off season. There isn’t any real pressure on the Atlanta airport right now. There’s just a bunch of thunderstorms. But here’s the real killer -- if you’re an air traffic controller.

”General Arrival Delays: Due to WX:Thunderstorms, arrival traffic is experiencing airborne delay between 1 hour and 1 minute and 1 hour and 15 minutes and increasing. “

If there are 1+ hour holding delays at the airport, that means there are somewhere between 68 to 126 airplanes holding for Atlanta. That’s what an hour’s worth of airplanes equals at ATL.

In really rough terms, ATL has 4 fixes aircraft arrive over -- from the NE, SE, SW and NW. Again, very roughly, there are 4 corresponding holding patterns at those fixes. If 68 (the low number) airplanes are split up evenly (they never are) you have airplanes holding at 4 different fixes from 11,000 to 27,000 feet. That’s 1,000 feet apart (altitude wise) from 11,000 MSL to FL270. (Do the math.)

I know not everybody is an air traffic controller but try to imagine what that looks like anyway. Four holding patterns -- 40 miles away from the airport -- occupied from 11,000 feet to FL270. That is a lot of airspace. And I’m being kind here. If I had used the 126 airplanes per hour figure each pattern would be full to FL410.

Basically, that’s every altitude available. If you could draw it out on a map, it would look like one great big road block in the sky. Maybe this will help you visualize it. Imagine all those straight lines from the NE, SE, SW and NW going in circles.

Flight Paths over Atlanta from Aaron on Vimeo.

What’s NextGen going to do about the weather ? Besides “nothing” ?

Image from Intellicast

Don Brown
January 24, 2010


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