Seeking ATL Insight

Pilot Hopeful

Well-Known Member
Coming into Atlanta (ATL) seems fairly standard, regardless of weather conditions: Fly the arrival, turn base, turn a 30-degree intercept to final, join the approach. We always seem to be three to five miles in trail of preceding traffic.

In general, any weather conditions reducing visibility or limiting visual approaches send ground stops or en route delays (e.g., slowing or holding) through the system. I realize that certain weather phenomena, such as thunderstorms, require avoidance and hence affect the ability to accept the normal rate of arrivals. However, the 1,000-foot overcast baffles me: Why does this seemingly benign condition create havoc on the operation? I am hoping that someone can provide ATC perspective on what we cannot perceive from the flight deck. When everything seems routine to us, what is triggering delay?

Sometimes conditions are CAVU . . . and we have the privilege of logging a hold over one of the arrival fixes. Are these delays due to traffic volume? If so, it is amazing to consider that such conditions exist when airlines have reduced flight schedules and are no where near full strength.
 

SpiceWeasel

Tre Kronor
Coming into Atlanta (ATL) seems fairly standard, regardless of weather conditions: Fly the arrival, turn base, turn a 30-degree intercept to final, join the approach. We always seem to be three to five miles in trail of preceding traffic.

In general, any weather conditions reducing visibility or limiting visual approaches send ground stops or en route delays (e.g., slowing or holding) through the system. I realize that certain weather phenomena, such as thunderstorms, require avoidance and hence affect the ability to accept the normal rate of arrivals. However, the 1,000-foot overcast baffles me: Why does this seemingly benign condition create havoc on the operation? I am hoping that someone can provide ATC perspective on what we cannot perceive from the flight deck. When everything seems routine to us, what is triggering delay?

Sometimes conditions are CAVU . . . and we have the privilege of logging a hold over one of the arrival fixes. Are these delays due to traffic volume? If so, it is amazing to consider that such conditions exist when airlines have reduced flight schedules and are no where near full strength.
While the airlines may have reduced their flight schedules, it doesn't necessarily mean ATL got a lot of those reductions. Flying here on a near daily basis it seems to me that we work the ATL Airport at full capacity on a CAVU day. Since separtion requirments change when you can't see anything, that's why it seems to grind to a screeching halt. I think the controllers do a great job with all of us crazy pilots buzzing around all over the place.

:rawk:
 

Pilot Hopeful

Well-Known Member
Oh, yes, the controllers do a fine job in Atlanta. The thread is NOT a criticism of ATC, just seeking some insight.

Good work Atlanta!
 

tykrtr

Well-Known Member
I don't work at ATL, but have talked to a few that do. From our facility, ATL has gotten infinitely better since the opening of the new runway. Before that, yikes! We used to say that someone saw a cloud in ATL and the ground delay program was at least 45 minutes.

Here's a decent site to see what's happening:
http://flightaware.com/live/airport/KATL
Open the blue map in the upper right corner in a new window and enjoy!

Even when the weather is "benign" by flying standards, the TRACON still has to run simultaneous ILS approaches (less than about 3000 & 5). When this happens they need extra controllers to act as "final approach monitors". Although the FAA will not admit to it, they are quite short staffed and finding 'extra' controllers is sometimes next to impossible. Even with perfect conditions, watch the 4 arrival corners and when too many aircraft show up, you'll still see a few people spin. It's simply too many people getting there at the same time. With three runways open, however, things usually get cleaned up pretty quickly.
 

Delta Romeo

New Member
I do work at ATL ATCT and can attempt to answer the question.

The comment about ATL operating at near capacity everyday is true, whether it’s IFR or VFR. When its VFR we can use visual separation (either we, the Tower, can see you and apply it as long as wake turbulence separation isn't involved, or you see the guy you're following and can apply it - which really helps when you're behind a B757 or a Heavy). This hugely expedites the flow. Think about it this way: We run over 2,000 operations daily. If you were to add a half-mile separation between every arrival, it would require an extra 1,000 miles of flight every day. Our airspace really isn’t that big…

Also another valuable point is that each set of parallel runways as sets (8/26 Left and Right, and 9/27 left and right) are separated by less then 2500 feet. This requires us to apply separation as if the parallels in each complex were 1 runway when we cannot see the arrivals. There is a radar rule that says we shall (this means its mandatory) separate an arrival from a departure (under this scenario) by having the departure rolling by the time the arrival reaches a 2 mile final. The rule actually says 2 miles increasing to 3 miles within 1 minute after departure. The key here is that the departure is ROLLING, not just cleared for takeoff when the arrival hits a 2 mile final. So, it helps when you guys go quickly when we say cleared for takeoff. Because of this rule, approach has to slow down the arrival rate so we can hit the gaps with the departures.

In the example you gave about a 1,000-foot OVC, when I can see the arrival I can let the departure roll, but inside of 2 miles until I can physically see that arrival...causes the same scenario as if it were OVC003. In circumstances where we cannot see out of the Tower windows at all (which happens a lot now that the Tower is 398 feet tall), we can use the ASDE-X (ground radar), and release the departure when the arrival crosses the threshold....also looking to make sure we have 2 increasing to 3 with the next arrival. It's very much like getting puzzle pieces to fit togther. So, you can see as a departure how much your quick cooperation helps the flow! If you don't roll quickly when we say go, it may require us to break the next arrival out and send him back out for resequencing. Thereby making even more delays.

There are other variables in the rules that come into play, but I think this gives you a good basic understanding of why it happens.
 

Pilot Hopeful

Well-Known Member
Thank you, Delta Romeo. You have provided great insight into the complexity of the operation. I figured it had to be more involved than what we see from the flightdeck.
 

SpiceWeasel

Tre Kronor
I do work at ATL ATCT and can attempt to answer the question.

The comment about ATL operating at near capacity everyday is true, whether it’s IFR or VFR. When its VFR we can use visual separation (either we, the Tower, can see you and apply it as long as wake turbulence separation isn't involved, or you see the guy you're following and can apply it - which really helps when you're behind a B757 or a Heavy). This hugely expedites the flow. Think about it this way: We run over 2,000 operations daily. If you were to add a half-mile separation between every arrival, it would require an extra 1,000 miles of flight every day. Our airspace really isn’t that big…

Also another valuable point is that each set of parallel runways as sets (8/26 Left and Right, and 9/27 left and right) are separated by less then 2500 feet. This requires us to apply separation as if the parallels in each complex were 1 runway when we cannot see the arrivals. There is a radar rule that says we shall (this means its mandatory) separate an arrival from a departure (under this scenario) by having the departure rolling by the time the arrival reaches a 2 mile final. The rule actually says 2 miles increasing to 3 miles within 1 minute after departure. The key here is that the departure is ROLLING, not just cleared for takeoff when the arrival hits a 2 mile final. So, it helps when you guys go quickly when we say cleared for takeoff. Because of this rule, approach has to slow down the arrival rate so we can hit the gaps with the departures.

In the example you gave about a 1,000-foot OVC, when I can see the arrival I can let the departure roll, but inside of 2 miles until I can physically see that arrival...causes the same scenario as if it were OVC003. In circumstances where we cannot see out of the Tower windows at all (which happens a lot now that the Tower is 398 feet tall), we can use the ASDE-X (ground radar), and release the departure when the arrival crosses the threshold....also looking to make sure we have 2 increasing to 3 with the next arrival. It's very much like getting puzzle pieces to fit togther. So, you can see as a departure how much your quick cooperation helps the flow! If you don't roll quickly when we say go, it may require us to break the next arrival out and send him back out for resequencing. Thereby making even more delays.

There are other variables in the rules that come into play, but I think this gives you a good basic understanding of why it happens.

Do you guys have any idea who the ramp controller guys are (I think they're probably employed by the carriers?)

Who the heck is it that always says "seeeeeeeeee ya!"
 

Delta Romeo

New Member
Ramp 1 & 2 Tower is Delta employees. Ramp 3 & 4, and Ramp 5 & 6, are operated by two seperate contractors. Don't know anyone who works there. Sorry.
 
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