ARTCC Requests

Owen Bliss

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ARTCC Requests
« on: September 08, 2018, 09:50:23 am »
Good morning,

I am currently flying from Dallas Love (KDAL) to Atlanta (KATL). Memphis center logged on and sent me a contact-me. My filed cruise altitude is FL390. I am over 200 miles from my top of descent (T/D) and the center controller instructed me to descend and maintain FL330. Upon questioning him on why I needed to descend to FL330. His response was "Per Atlanta Centers request". Now keep in mind, Atlanta Center is currently offline. I am looking at the real flight I am following and they have just started there descent, but they are also about 30 mins ahead of me. I responded back to center informing him that I would not be able to descend to FL330 due to the fact that I would be using my reserve fuel into Atlanta.So now I am cruising at FL370. Is there any reason why I would be instructed to descend so early? I do understand that there are certain LOAs, and SOPs. But this is a first.

« Last Edit: September 13, 2018, 08:37:25 am by Owen Bliss »

Odin Morris

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Re: ARTCC Requests
« Reply #1 on: September 08, 2018, 10:00:54 am »
Per ZME - ZTL LOA all aircraft arriving into ATL or ATL Satellites are to cross the ZME - ZTL boundary AOB FL330. So that would be why.

I'd assume the reason they followed this without an Atlanta Center online is due to the possibility of them signing on. You should always follow LOAs even when the other controller is not online.

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Matt Bromback

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Re: ARTCC Requests
« Reply #2 on: September 08, 2018, 10:28:32 am »
Good mroning,

I am currently flying from Dallas Love (KDAL) to Atlanta (KATL). Memphis center logged on and sent me a contact-me. My flied cruise altitude is FL390. I am over 200 miles from my top of descent (T/D) and the center controller instructed me to descend and maintain FL330. Upon questioning him on why I needed to descend to FL330. His response was "Per Atlanta Centers request". Now keep in mind, Atlanta Center is currently offline. I am looking at the real flight I am following and they have just started there descent, but they are also about 30 mins ahead of me. I responded back to center informing him that I would not be able to descend to FL330 due to the fact that I would be using my reserve fuel into Atlanta.So now I am cruising at FL370. Is there any reason why I would be instructed to descend so early? I do understand that there are certain LOAs, and SOPs. But this is a first.

As a good rule of thumb you should always plan for 45 minutes of reserve fuel plus contingency fuel (usually about 15-30 minutes extra). Descending from FL390 to FL330 should not cause a big difference in fuel burn for the remainder of the flight, sounds like you were a little low of fuel to begin with. Also when ATC issues a early descent its a good rule of thumb to "re-cruise" the FMC so go to CRZ page and put in FL330. This will change your TOD as well as your fuel burn for arrival, if this is not done this may cause errors in fuel burn for destination.
Matt Bromback

Matthew Kramer

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Re: ARTCC Requests
« Reply #3 on: September 09, 2018, 12:51:43 am »
Per ZME - ZTL LOA all aircraft arriving into ATL or ATL Satellites are to cross the ZME - ZTL boundary AOB FL330. So that would be why.

I'd assume the reason they followed this without an Atlanta Center online is due to the possibility of them signing on. You should always follow LOAs even when the other controller is not online.

At or At or Above? Curious where in Memphis' airspace this took place. In ZLA I'll often issue a PD to 240 for airplanes arriving LAX. Sometimes pilots mishear that as "Descend Now" instead of "Descend Pilot's Discretion."
Matthew Kramer
ZLA DATM

Odin Morris

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Re: ARTCC Requests
« Reply #4 on: September 09, 2018, 06:59:31 am »
Per ZME - ZTL LOA all aircraft arriving into ATL or ATL Satellites are to cross the ZME - ZTL boundary AOB FL330. So that would be why.

I'd assume the reason they followed this without an Atlanta Center online is due to the possibility of them signing on. You should always follow LOAs even when the other controller is not online.

At or At or Above? Curious where in Memphis' airspace this took place. In ZLA I'll often issue a PD to 240 for airplanes arriving LAX. Sometimes pilots mishear that as "Descend Now" instead of "Descend Pilot's Discretion."

At or below (AOB). Usually pilots are told to descend at pilots discretion but more times then not they would descend immediately.

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ZDV - Denver ARTCC

Brin Brody

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Re: ARTCC Requests
« Reply #5 on: September 09, 2018, 07:58:13 am »
Per ZME - ZTL LOA all aircraft arriving into ATL or ATL Satellites are to cross the ZME - ZTL boundary AOB FL330. So that would be why.

I'd assume the reason they followed this without an Atlanta Center online is due to the possibility of them signing on. You should always follow LOAs even when the other controller is not online.

At or At or Above? Curious where in Memphis' airspace this took place. In ZLA I'll often issue a PD to 240 for airplanes arriving LAX. Sometimes pilots mishear that as "Descend Now" instead of "Descend Pilot's Discretion."

At or below (AOB). Usually pilots are told to descend at pilots discretion but more times then not they would descend immediately.

Probably done right before the ZTL-ZME shelf airspace that lets us descend aircraft into ATL as soon as we get them.  Typically ZME will handoff descending to FL330 (usually within 2000ft at the time of the handoff) in that shelf. Others have already answered the LOA's discussion on altitude.
Brin Brody
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Jacksonville ARTCC
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Matthew Kramer

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Re: ARTCC Requests
« Reply #6 on: September 10, 2018, 02:12:06 pm »
Per ZME - ZTL LOA all aircraft arriving into ATL or ATL Satellites are to cross the ZME - ZTL boundary AOB FL330. So that would be why.

I'd assume the reason they followed this without an Atlanta Center online is due to the possibility of them signing on. You should always follow LOAs even when the other controller is not online.

At or At or Above? Curious where in Memphis' airspace this took place. In ZLA I'll often issue a PD to 240 for airplanes arriving LAX. Sometimes pilots mishear that as "Descend Now" instead of "Descend Pilot's Discretion."

At or below (AOB). Usually pilots are told to descend at pilots discretion but more times then not they would descend immediately.

I read AOA because reading comprehension.
Matthew Kramer
ZLA DATM

Owen Bliss

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Re: ARTCC Requests
« Reply #7 on: September 11, 2018, 08:40:37 am »
Thanks for the replies. My concern was the fact that I had just contacted center to the west at FL390 at the border. When I checked in he told me to descend. I understand descending before/near the border, but I wasn't even at cruise for 15 mins before I was descending to FL330 to cross the border when I was a few hundred miles from the border.

Dylan Lundberg

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Re: ARTCC Requests
« Reply #8 on: September 12, 2018, 12:05:20 am »
Thanks for the replies. My concern was the fact that I had just contacted center to the west at FL390 at the border. When I checked in he told me to descend. I understand descending before/near the border, but I wasn't even at cruise for 15 mins before I was descending to FL330 to cross the border when I was a few hundred miles from the border.

What instruction did he give you:

A) Descend at pilots discretion, maintain FL330"
B) Descend and maintain FL330.

Either way, LOAs are in effect for a reason, so  you should always comply with the controllers instructions. Definetley advise reading the above replies for FMS operation regarding fuel burn, as well.

Blue Skies!
Dylan Lundberg
Air Traffic Manager
Honolulu Control Facility


Cardin Pelletier

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Re: ARTCC Requests
« Reply #9 on: September 12, 2018, 02:23:13 am »
Owen,

Thanks for flying through and for your question. Many here have already done a great job of answering your question.  I wasn't there, so I cant answer specifically to why the controller on position gave the instruction. What I can say is that this is a normal instruction for Atlanta arrivals. Typically, we do not issue the descent that far out as you are describing. However, it's important to remember that we will issue altitude instructions for several different reasons, some of which may or may not be obvious to the pilot. It could be traffic, an agreement between adjacent sectors or facilities, or airspace. In general, we like to allow the pilots to fly the speeds, altitudes, and routings that they file -- we understand those things are chosen for a reason. Although our primary responsibility is separating traffic, we also have to provide for the safe, orderly, and expeditious flow of it. You may occasionally receive a more or less economic altitude, a more or less desirable routing or speed to achieve those goals.

Others have already touched on this, but many times we will issue "pilot-discretion" descents. We experience many pilots who fly through the airspace and misunderstand this clearance. I can't be certain, but it is definitely possible this was the cause of a misunderstanding in your case. It's important to recognize the difference between receiving a "PD" descent and a hard altitude. If given a pilot-discretion descent, the controller will use the phrase "...descend at pilot discretion..." followed by an altitude to maintain. In such a case, the pilot need not start the descent immediately. You may begin your descent, as the clearance implies, at your discretion. If a controller gives you a hard altitude, they will use the phrase "...descend and maintain..." followed by an altitude. If given this clearance, the pilot should start a descent promptly to the assigned altitude. We expect jets to descend at a rate of at least 1,000 feet per minute when we instruct an aircraft to "climb/descend and maintain...".

As someone already suggested, its a good idea to take on a little bit of extra gas to protect against any unforseen delays, such as being descended early, vectoring, reroutes, holding, etc. You as the pilot have to make the determination of what you're comfortable with as far as the fuel goes, but I will say it is perfectly okay to burn into your reserve fuel -- you just cant plan to use it when pre-flight fuel planning (it has to be in addition to the fuel required to fly from A-B and from B to your furthest alternate).

I cant say whether or not the controller made a judgement error or whether the early descent as you described it was necessary, but I will say you did the correct thing by advising the controller that the descent would put you in an uncomfortable fuel situation. We can almost always coordinate and get you what you need when it comes to those types of scenarios.

Please feel free to send me an e-mail directly if you have any other questions and I will be happy to respond via e-mail or meet with you on our Teamspeak to discuss them.

Best Regards,

Cardin Pelletier
vZME Training Admin
TA@vzmeartcc.com

Robert Shearman Jr

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Re: ARTCC Requests
« Reply #10 on: September 12, 2018, 03:33:51 pm »
"...descend at pilot discretion..." {...} In such a case, the pilot need not start the descent immediately.
... and in an airliner with a standard FMC the usual pilot input is to adjust the cleared altitude on the Autopilot Master Control Panel (front dashboard) to the new cleared altitude, and let the FMC manage the descent's starting point and rate.

If a controller gives you a hard altitude, they will use the phrase "...descend and maintain..." followed by an altitude. If given this clearance, the pilot should start a descent promptly to the assigned altitude. We expect jets to descend at a rate of at least 1,000 feet per minute
And as a pilot you can either (a) put the plane into a Vertical Speed hold at -1000fpm until the VNAV path "catches up with you," then re-engage VNAV; or, some FMCs have a "DESCENT" page where you can activate a "DES NOW" mode which manages all of that for you.

... and, apologies if the original poster is already aware of that.  I'm just posting this info for anyone else who runs across it and wants verification on how the two situations can be handled from the pilot's perspective.
Cheers,
-R.

Ryan Geckler

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Re: ARTCC Requests
« Reply #11 on: September 12, 2018, 06:41:58 pm »
Good explanation, Robert.

I'd also make sure that you guys (as an ATO) really enforce not changing the MCP altitude until cleared to a different altitude. A common error is that pilots read the STAR and see it's a descend via, so they change the MCP altitude to the bottom of the STAR, and just descend on their own. Usually it's harmless if it happens, but there's going to come a time where that happens and it causes issues.
Ryan Geckler - GK
Former VATUSA3 | Division Training Director
Minneapolis ARTCC | RW Miami ARTCC