30 NM required separation - Really?

iflyvfr

iflyvfr

Pattern Altitude
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Greg
A co-worker got stuck Wed/Thu trying to get out of San Antonio and over to KATL for his connecting flight on Delta. His flight was epic delayed. He ultimately ended up booking a ride from DFW to CMH direct via AA and renting a car from San Antonio to DFW and driving thru the night to catch it.

Anyway, during his efforts to secure a flight home he was told that part of the problem was that A/C departing ATL during a lull in all the storms were required to reach a point 30 NMs distant from the field before the next AC was allowed to depart - thereby compounding the delays.

What's up with that?
 
I was on one of those planes leaving ATL. Couldn't believe it when the pilot said that; it's usually 3-5 nm . . .
 
Atc radar failure?


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Sounds like flow restrictions. Here is how this goes normally and with wx flow involved. Normally Center provides 10 20 in trail to me depending on request. Our reasoning is 4 arrival streams, 5 in trail, 4/ 5 = 20. 5 in trail btw normally begets min sep over the numbers. TRACONS can and will request additional sep depending on conditions.

Now put yourself in the departure TRACON or receiving ATRCC controller's shoes. I need 30 left and right to deviate. Epic storm is stagnating over X departure/arrival fixes. We call this going one route. Its done to ensure that min sep in maintained when conditions require pilots to refuse their DP/SID once they swing radar that way. The alternative is to bust sep or keep you down low while the crj 200 struggles out of 300.

Extra sep comes in to play when one poor controller with the only clear skies realizes your sector in Montana is now the only clear shot to flow JFK/LAX. Congrats you just quadrupled your work load. If its me an my rate goes up 4X, GDP like yesterday.
 
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That makes a lot of sense now, my guy will surely appreciate knowing. Helps me appreciate how much smaller the bigger picture can be when there is lots of WX out there.

GDP = Grand Daddy Purple? :eek:
 
Thanks for that exceptionally useful answer, Mr. Approach Controller. While we ought to be able to visualize it from looking at terminal areas with big storms around, your description is much better!
 
Pretty normal when there are flow restrictions. Approach controller nailed it.
 
It translates to about a 7 minute delay between takeoffs.
 
iflyvfr said:
A co-worker got stuck Wed/Thu trying to get out of San Antonio and over to KATL for his connecting flight on Delta. His flight was epic delayed. He ultimately ended up booking a ride from DFW to CMH direct via AA and renting a car from San Antonio to DFW and driving thru the night to catch it.

Anyway, during his efforts to secure a flight home he was told that part of the problem was that A/C departing ATL during a lull in all the storms were required to reach a point 30 NMs distant from the field before the next AC was allowed to depart - thereby compounding the delays.

What's up with that?
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Do you know if they were getting some departures off going in other directions between the 30 in trail guys. A flat 30 between everything, during a lull in the storms seems a bit much
 
TMU (traffic management unit) restrictions. Could be for anything but certainly due to flow. By the time aircraft are allowed to leave there is such a backlog that arrival routes to destination airports in other parts of the country can easily get backed up. Especially if several aircraft are going to the same place. The 30 miles may be to allow room for 2 other aircraft (10 in trail) to join into the line 500 miles from ATL. Or gate availability intervals at receiving airports once the hounds are released.

Metering and spacing of inbound aircraft can start on departure especially during rushes and heavy, sudden releases.

tex
 
luvflyin said:
Do you know if they were getting some departures off going in other directions between the 30 in trail guys. A flat 30 between everything, during a lull in the storms seems a bit much
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Sorry, I do not know. I doubt my colleague would have thought to ask - he is not tuned into aviation at all. Thanks to everyone who took the time to answer my question!
 
luvflyin said:
Do you know if they were getting some departures off going in other directions between the 30 in trail guys. A flat 30 between everything, during a lull in the storms seems a bit much
Click to expand...
Yes. The ground controller with move the airplanes around to put them in the correct sequence that will result in the proper in trail spacing. You'll see this often when taxiing out at large airports. You'll pass other airplanes, or will be passed by others, during taxi out.
 
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