Making Sense Of “Climb Via” And “Descend Via”

Making Sense Of “Climb Via” And “Descend Via”

Almost two years ago, Air Traffic Controllers began issuing a new clearance relating to Standard Instrument Departure (SID) procedures. You may have heard the following clearance or something similar; “N716RM, proceed direct GOPHER, climb via the KBREW SEVEN departure.” If that sends a chill, you aren’t alone. The “climb via” clearance (and its older cousin, “descend via”) can be tricky to understand. And failure to comply with these clearances can result in a pilot deviation being filed by the FAA. Let’s review the concepts, so you can accept these clearances with the confidence of an appropriately-seasoned airline pilot.

To quote the Pilot/Controller
Glossary, the “climb via” clearance is:

“An abbreviated ATC clearance that requires compliance with the procedure’s lateral path, associated speed restrictions, and altitude restrictions along the cleared route or procedure”.

In short, ATC uses the “climb via” clearance to minimize radio calls. Rather than issuing numerous “climb and maintain” or “fly heading…” clearances, ATC will issue one clearance, with the assumption that the pilot will meet the lateral and vertical requirements depicted on the SID chart. ATC expects the pilot to meet all of the altitude crossing restrictions indicated on the chart. If your aircraft cannot meet the climb gradient requirements of a SID, notify ATC prior to accepting the clearance or by including NO SID in the remarks section of the IFR flight plan.

Typically, the “climb via” clearance will be part of your initial IFR clearance. It will sound something like this:

“Superjet 123, you are cleared to the San Diego airport, BAYLR THREE departure, TEHRU transition, climb via the SID, expect runway three five left for departure”.

09077BAYLR

When you receive a climb via clearance, be sure to take some time to familiarize yourself with the procedure. If you need extra time to prepare, request your IFR clearance prior to starting engines. You can typically request the clearance up to 30 minutes prior to your scheduled departure time. This is also a good time to mention that ATC is expecting you to read the “climb via” clearance back verbatim, including your aircraft call sign. You cannot abbreviate the read-back of a climb via clearance.

Let’s take a look at the BAYLR THREE departure at Denver in more detail.

The first thing you should determine is the published top altitude for the procedure, depicted on the upper right-hand corner of the chart – FL230. This is the top of the climb via clearance. It’s possible for ATC to amend this top altitude. I’ve underlined the top altitude in the example transcript for an amended clearance below.

“Superjet 123 you are cleared to the San Diego airport, BAYLR THREE departure, TEHRU transition, climb via the SID except maintain one seven thousand, expect runway three five left for departure”.

In this example, ATC amended the top altitude to 17,000. We are still required to meet all of the remaining crossing restrictions but stop the climb at 17,000 until receiving further clearance. It’s also possible that a departure procedure does not have a published top altitude, although top altitudes are being added to most departure procedures when they are updated. Have a look at the KBREW SEVEN departure procedure for the Minneapolis airport below. You won’t find a published top altitude. For this reason, the ATC clearance will include a top altitude in the initial clearance. I’ve underlined the top altitude in the transcript below.


00264KBREW_C

“Superjet 123 you are cleared to the Fargo airport, KBREW SEVEN departure, Fargo transition, climb via the SID except maintain one six thousand”.

After we’ve identified our top altitude, we should familiarize ourselves with all applicable climb gradient requirements. Returning to the BAYLR THREE example, we see that there is an initial climb requirement after departing runway 35L: climb at 400 feet per nautical mile (NM) to 5,934, then climb at 260 feet per NM to 16,500. If we are able to satisfy this climb gradient requirement, we can accept this departure procedure.

Finally, we should plan our departure and climb profile. In the BAYLR THREE example, we can reference the back side of the chart for a narrative of the takeoff requirements. Not all SIDs will include a detailed narrative, but if the chart has a narrative, you should read it carefully – it’s likely a complex procedure that will require your attention. For our BAYLR THREE departure from 35L, we are required to climb on a runway heading until we reach 5,934, then turn left direct to CRAGR while continuing our climb. We have to be sure that we cross CRAGR at or below 10,000, then continue on to HAWPE intersection while we continue our climb to cross TUULO at or above 12,000. Next, we need to cross the HLTON intersection at or above 14,000, then MTSUI at or above 16,000. Finally, we continue our climb (at this point without any restrictions) up to our top altitude (FL230 unless amended by ATC) while navigating to BAYLR, then BOBBA, then on course. This departure procedure does not have any speed restrictions. If there are specific speed restrictions, you will be required to comply with these restrictions as well.

There are a couple of more things you should be aware of regarding the climb via clearances. It’s possible that ATC will give you a temporary amendment to the climb via SID. If they are working you around traffic, they can vector you off of a SID or ask you to level at an intermediate altitude. That would sound something like this:

“Superjet 123, fly heading two two zero and maintain one four thousand. Expect to resume the SID”.

In this case, you are required to comply with these new restrictions and temporarily disregard the charted restrictions of the SID. Once you are clear of the traffic, they will likely clear you back onto the SID (“proceed direct HAWPE, resume the BAYLR THREE”) and you will again be required to meet the lateral and vertical restrictions while climbing to the top altitude, FL230.

I’ll end the climb via discussion with one tricky example. Let’s look at the EPKEE THREE departure at Denver.

09077EPKEE

Step 1: Find the top altitude.

In this case, it’s in the bottom right-hand corner of the chart.


Step 2: Identify climb gradient requirements.

Assuming we depart from runway 35 left we need to climb at 400 feet per NM to 5,934, then 230 feet per NM to 14,000.

Step 3: Plan out the departure and climb profile.

Again, assuming a departure from runway 35 left, we need to cross KIDNG at or below 10,000 and APUUU at or above 14,000. Have a look at the CLAMR intersection. It has a crossing restriction of FL300 (at or above FL300). This is above the published top altitude (FL230). You may not climb above FL230 until specifically cleared by ATC. Reading the narrative on the back of the departure procedure will help clarify this restriction. There are no speed restrictions for this departure procedure.

So, right after takeoff from runway 35 left, we will climb on a runway heading (353°) until reaching 5,934, then initiate a climbing right-hand turn to the KIDNG intersection, then continue to the fixes depicted on the chart, being sure to stop at the top altitude of FL230.

Coming Back Down

Now, let’s briefly visit an old concept that goes along with this topic, relating to Standard Terminal Arrival Routes (STARs), the “descend via” clearance. These clearances have been used for some time but I think it’s good to review them.

It used to be that only a handful of airports utilized a STAR in which ATC would issue a “descend via” clearance, La Guardia’s KORRY Arrival being the foremost in my memory. Now these STARs are quite common and it’s becoming more likely that a pilot will hear a descend via clearance during his arrival into a moderately-busy airport. It’s important for the pilot to know what this clearance means and what ATC expects of them.

First, to clarify what I’m talking about when I say a “descend via” clearance, I will use the CRAZI ONE RNAV Arrival into the Billings Logan International Airport.

So what is a descend via clearance? The Pilot/Controller glossary in the back of the AIM offers the following definition:

An abbreviated ATC clearance that requires compliance with a published procedure lateral path and associated speed restrictions and provides a pilot-discretion descent to comply with published altitude restrictions.

The typical descend via clearance will sound something like this:

Delta 1428, expect to land runway 28R, cross BYRCH at or above FL200, then descend via the CRAZI ONE Arrival, maintain 5,000, Billings altimeter 30.12.

That’s it; really not a very complicated clearance. But what does it mean?

That’s a little more complicated. Essentially, ATC wants you to follow the lateral and vertical depiction indicated in the STAR. It’s a little like flying a non-precision approach that begins 100 NM from the airport. You will note that the STAR has numerous altitude “tags” that depict a minimum altitude (at or above 17,000), a maximum altitude (below 10,000), a hard altitude (at 7,000) or a range of altitudes (below 7,000 and at or above 4,000). When given a descend via clearance, the pilot must plan his descent to meet every one of these altitude restrictions without interaction from ATC; they will expect you to meet these crossing restrictions on your own. Some STARs also include speed restrictions (At 10,000 and 250 KTS). ATC expects you to meet these speed restrictions as well.

00048CRAZIThat’s really all there is to it. Let’s look at the Billings example again. Based on the clearance given, we would plan our descent to cross TYMBR at or above 17,000′ MSL, IGIFE at 210 KTS and 9,500′ and HYTES at or above 6,200’ MSL while descending to 5,000′ MSL. A descend via clearance doesn’t preclude ATC from issuing amendments to what is published, either by issuing an amended clearance or by NOTAM. This is a really good reason to check those FDC NOTAMS very carefully. I remember when Reagan National Airport in Washington, DC was developing descent procedures for the WZZRD (now named the FRDMM) arrival. The altitudes indicated on the chart were amended pretty consistently by NOTAM. Read those NOTAMS carefully! It’s also important to note, if you don’t understand what ATC is wanting from you, ask!

It’s far better to clear up any confusion prior to getting an altitude violation.

Let’s close with another example. Memphis has a pretty complex RNAV Arrival procedure that’s used with a “descend via” clearance quite often. It’s the BRBBQ ONE Arrival. Look carefully at all of the altitude and speed restrictions on this arrival. Look closely at the BRBBQ intersection; at 280 KT and at or below FL230. Now look at FNCHR, only 11 NM down the road; between 16,000 and 14,000. If you crossed BRBBQ exactly at FL230 then tried to meet the crossing restriction at FNCHR, that’s an altitude loss of 7,000′ over a distance of 11 NM! A 3-degree descent angle would require 21 NM; that’s 10 NM more than you have. The lesson here is that you really need to be proactive in planning these descents early on. If we are going to make the restriction at FNCHR, we will have to be around FL200 by BRBBQ, assuming we follow a 3-degree descent angle.

00253BRBBQ

Now, for some appropriately seasoned barbeque, visit the Germantown Commissary in downtown Memphis. It’s a small place with excellent barbeque and great southern hospitality. If you come up with any specific questions, don’t hesitate to ask: . shayne@flyvift.com.T&T

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