"Descend Via"

Wesley Miles

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"Descend Via"
« on: November 02, 2013, 10:19:29 PM »
Who here issues "Descend Via" instructions to aircraft on an RNAV STAR working a CTR position?  I spoke with a real world CTR controller recently who told me ARTCC's are not authorized to use that phraseology-- that it's reserved only for TRACONs (with the exception of ZAB... I believe).  Has anyone else heard this?  If so, where is the documentation?

When looking at 7110.65 4-5-7... it's pretty evident to me that "Descend Via" can be issued by either ENROUTE or TERMINAL.  I know there was a notice (N JO 7110.584) which added "Climb Via", then another notice which cancelled that (N JO 7110.597)... but neither appear to affect "Descend Via" which provides provisions for both Terminal and Enroute.

Thoughts?
Wes Miles
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Ryan Geckler

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"Descend Via"
« Reply #1 on: November 02, 2013, 11:49:29 PM »
I think that the 7110 is current in regards to descend via. ZDC uses it on a daily basis.

Out of curiosity, where does your source work?
Ryan Geckler - GK
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Wesley Miles

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"Descend Via"
« Reply #2 on: November 03, 2013, 09:19:23 AM »
If I remember correctly, he was at ZBW.  Met him through VATSIM a few months ago but can't remember his name now.
Wes Miles
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Harold Rutila

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"Descend Via"
« Reply #3 on: November 03, 2013, 10:50:39 AM »
ZLA has been using it for years. ZDV just started about a year ago with the introduction of RNAV STARs. "Climb via" is not approved. An IFR clearance containing an RNAV SID implies that the pilot will climb via the procedure unless otherwise instructed. I spoke to an FAA employee who works directly with the .65 a few months back, and he said there are numerous squabbles within the FAA as to how they want to address handling of RNAV procedures on the whole. I'd expect some changes within the next few years compared to how things are done now.

Dhruv Kalra

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"Descend Via"
« Reply #4 on: November 03, 2013, 06:42:01 PM »
ZBW is unable to use "Descend via" with their RNAV arrivals due to conflicting traffic flows that cross their STAR routes. Boston TRACON issues the final "Descend via" instruction within the terminal environment once the aircraft's vertical path is clear of conflict.

Further reading on this specific to ZBW: http://nas-confusion.blogspot.com/2012/03/...-are-happy.html
Dhruv Kalra
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Scott DeWoody

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"Descend Via"
« Reply #5 on: November 04, 2013, 06:23:37 AM »
Quote from: Dhruv Kalra
ZBW is unable to use "Descend via" with their RNAV arrivals due to conflicting traffic flows that cross their STAR routes. Boston TRACON issues the final "Descend via" instruction within the terminal environment once the aircraft's vertical path is clear of conflict.

Further reading on this specific to ZBW: http://nas-confusion.blogspot.com/2012/03/...-are-happy.html

Depends on the situation.  At 4am, with little or no traffic, they bend the rules a little at times.  ie arrival on a STAR they use "at pilot discretion" and "decend via" a lot if there are no or little aircraft around.  This comes from a friend that is a real world AA pilot.
Scott DeWoody

Brad Littlejohn

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"Descend Via"
« Reply #6 on: November 04, 2013, 12:16:42 PM »
Quote from: Scott DeWoody
Depends on the situation.  At 4am, with little or no traffic, they bend the rules a little at times.  ie arrival on a STAR they use "at pilot discretion" and "decend via" a lot if there are no or little aircraft around.  This comes from a friend that is a real world AA pilot.

Not only that, but when you have a CTR position open handling the Terminal area (as APP), they are going to be issuing that instruction anyway. If APP is on, there will be that line of separation there as to who issues the call.

At most RW facilities, that position is always manned, so they never will run into that problem. For us, it is different, because it will never be manned 24/7.

Me personally, I'll issue the crossing restriction first, as required by SOP/LOA between the TRACON and ARTCC facility, and then after they meet that, give the 'descend via' call. If there is little/no traffic around at that time, I might give the 'descend via' all. I say 'might', because of what the initial crossing restriction may be.

Example: the SUNST3 arrival into KLAS explicitly has its first crossing restriction to be at FUZZY at 16000ft, 250kts. So for that one, again, if no traffic is around at all, give the 'descend via' call. Same would apply with the SEAVU2 arrival into KLAX.

However, the RIIVR2 arrival into KLAX, the first crossing restriction is at GRAMM at/below FL210, and at/above 17000ft, at 280kts. That would imply that a crossing restriction is needing to be given. So I may issue two separate calls, or combine them:

'Cross GRAMM at xxx' (depending on altimeter setting), then when they cross GRAMM, issue 'descend via'..

Or they could be combined: 'cross GRAMM at xxx, then descend via'.

For the latter, Las Vegas TRACON does issue that at times for aircraft that may be high or to give a bit of leeway on the SUNST3 or KEPEC3. They'll say something like 'cross IPUMY at 11,000, then descend via'.

BL.

Dhruv Kalra

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"Descend Via"
« Reply #7 on: November 04, 2013, 01:17:20 PM »
Quote from: Brad Littlejohn
However, the RIIVR2 arrival into KLAX, the first crossing restriction is at GRAMM at/below FL210, and at/above 17000ft, at 280kts. That would imply that a crossing restriction is needing to be given. So I may issue two separate calls, or combine them:

'Cross GRAMM at xxx' (depending on altimeter setting), then when they cross GRAMM, issue 'descend via'..
Wouldn't "Descend via the RIIVR2" allow an aircraft to cross GRAMM between 17,000 and FL210 at 280 KIAS? The block altitude doesn't necessitate a crossing restriction. Any SOP/LOA between ZLA and SCT would, however.
Dhruv Kalra
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Brad Littlejohn

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"Descend Via"
« Reply #8 on: November 05, 2013, 12:17:49 PM »
Quote from: Dhruv Kalra
Wouldn't "Descend via the RIIVR2" allow an aircraft to cross GRAMM between 17,000 and FL210 at 280 KIAS? The block altitude doesn't necessitate a crossing restriction. Any SOP/LOA between ZLA and SCT would, however.

You're right, it would. However, you are also correct about SOPs. SCT has control on descent for the arrivals coming in on that STAR, and SOP does set a hard crossing altitude for the arrivals. so we issue that crossing restriction, and hand them off prior to crossing SCT's lateral boundaries, and let them handle that descent. When not available, we're acting as APP during the descent, so that would give the CTR controller a bit more leeway in how they would handle the descent.

BL.

Tim Farrell

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"Descend Via"
« Reply #9 on: November 06, 2013, 11:57:10 AM »
Correct me if I am wrong, but my take on the descend via according to the 7110 is that if there is the word "expect"  on the STAR either rnav and non-rnav, a controller cannot use the phrase "descend via". There are some rnav arrivals that have the word "expect with the crossing" and some do not. I believe DEN has a STAR that you can "descend via." Not sure there are many of those types around. According to real world FTW_CTR controllers DFW will be getting all new arrivals that will be rnav sometime in 2014. Currently, vZFW doesn't have any arrivals  that would mandate a controller to use the phrase "descend via..." on the arrivals. I am hearing "decsend via" a lot in Vatusa where technicaly, this is incorrect in most cases.
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Brad Littlejohn

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"Descend Via"
« Reply #10 on: November 06, 2013, 12:48:38 PM »
Quote from: Tim Farrell
Correct me if I am wrong, but my take on the descend via according to the 7110 is that if there is the word "expect"  on the STAR either rnav and non-rnav, a controller cannot use the phrase "descend via". There are some rnav arrivals that have the word "expect with the crossing" and some do not. I believe DEN has a STAR that you can "descend via." Not sure there are many of those types around. According to real world FTW_CTR controllers DFW will be getting all new arrivals that will be rnav sometime in 2014. Currently, vZFW doesn't have any arrivals  that would mandate a controller to use the phrase "descend via..." on the arrivals. I am hearing "decsend via" a lot in Vatusa where technicaly, this is incorrect in most cases.

You are quite correct here. But the other thing to realize is that they don't have to be RNAV for the airport in question.. it's mainly profiled descents that are the tale of the tape. Cases in point: RIIVR2 and SEAVU2 arrivals into LAX. The thing that I think is also confusing people is that the FAA has omitted using the word "cross at <altitude>", instead opting for the lines above, below, or both above and below the altitude depicted. So some controllers aren't used to seeing that, and may not know how to handle it.

BL.

Bradley Grafelman

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"Descend Via"
« Reply #11 on: November 06, 2013, 12:54:15 PM »
Quote from: Tim Farrell
Correct me if I am wrong, but my take on the descend via according to the 7110 is that if there is the word "expect"  on the STAR either rnav and non-rnav, a controller cannot use the phrase "descend via".
... until after issuing "cross SMFIX at 10,000" (which is in the examples in this thread so far). That is, unless you're referring to a STAR that does not just begin with an "expect to cross at.." with hard crossing restrictions afterwards?

Quote from: Tim Farrell
I am hearing "decsend via" a lot in Vatusa where technicaly, this is incorrect in most cases.
Any specific examples come to mind? To your point above, one example might be the VISTA2 arrival into KLAX.

With this STAR, saying "cross CYNDE at 12,000, then descend via the VISTA2 arrival" would be an example of an invalid instruction.
« Last Edit: November 06, 2013, 12:56:06 PM by Brad Grafelman »

Tim Farrell

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"Descend Via"
« Reply #12 on: November 06, 2013, 06:09:30 PM »
The Vista2 would not be a candidate for the "descend via..." phraseology. The words "Expect to cross..." invalidate the use of the phraseology if I am reading the 7110 correctly.
Tim Farrell, FDC1601
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Adam Smith

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"Descend Via"
« Reply #13 on: November 06, 2013, 06:39:18 PM »
I've interpreted it as you can only issue the "descend via" instructions if the STAR has hard altitudes, (line above and below) otherwise you descend them manually. As for the OP. If the TRACON is staffed below, I don't see how Center can issue a "decend via" as it would bust the TRACON airspace, unless of course there is an SOP to that effect
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Ryan Geckler

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"Descend Via"
« Reply #14 on: November 07, 2013, 09:57:53 AM »
Quote from: Tim Farrell
The Vista2 would not be a candidate for the "descend via..." phraseology. The words "Expect to cross..." invalidate the use of the phraseology if I am reading the 7110 correctly.

Correct. You can't use it.


Quote from: Adam Smith
I've interpreted it as you can only issue the "descend via" instructions if the STAR has hard altitudes, (line above and below) otherwise you descend them manually.


Yup. See the FRDMM2 arrival into DCA. That's a "descend via" arrival.


Ryan Geckler - GK
VATUSA9 | Traffic Management Unit Director
Former VATUSA3 | Division Training Director
Minneapolis ARTCC | RW Miami ARTCC