Story ID: 
AINsight: Avoiding RNAV SIDs and STARs Gotchas
By: Stuart “Kipp” Lau
Caption: Climb and descend via clearances still tripping up pilots
Word Count: 1365
In 2014, the FAA introduced new and revised air traffic procedures that included “climb via,” “descend via,” and speed adjustment clearances for pilots flying RNAV departures (SIDs) and arrivals (STARs). Remarkably, in the 10 years since, pilots continue to make mistakes complying with these ATC clearances. As a result, altitude (vertical), course (lateral), and speed deviations are often cited as the most common reasons for a pilot to submit a NASA ASRS or ASAP report.
Recognizing the complexities of these new procedures, NBAA’s Domestic Operations Committee has published “Pilot Briefing: Climb Via, Descend Via, Speed Adjustments,” which covers the nuances of each procedure and the subtle differences between procedures around the world, including the FAA, ICAO, and Nav Canada.
According to the document, the goal of these updated procedures was to reduce radio frequency congestion, reduce the number of hear-back and read-back errors, and provide worldwide harmonization of ATC clearances. By design, these procedures were intended to provide “simple, intuitive phraseology for issuing a clearance to laterally and vertically navigate a departure or arrival.”
At a minimum, pilots must be familiar with the basic application of these types of clearances:
Climb via (to published top altitude): An abbreviated ATC clearance that requires compliance with a procedure’s lateral path, associated speed restrictions, and altitude restrictions along the cleared route or procedure until climbing to the top altitude published on the SID.
Descend via (to published bottom altitude): An abbreviated ATC clearance that requires compliance with a published procedure’s lateral path and associated speed restrictions and provides a pilot-discretion descent to comply with published altitude restrictions until descending to the bottom altitude published on the STAR.
Easy enough, right? A climb via or descend via clearance has the pilot fly the procedure in its entirety (adhering to all published speed and altitude constraints) to its respective top or bottom altitude.
But the next two variations of this procedure often confuse pilots and thus frustrate air traffic controllers:
Climb/descend via except maintain (to an ATC-assigned top/bottom altitude): Execute a climb via or descend via clearance to an ATC-assigned top altitude or bottom altitude, respectively. A climb/descend via except maintain clearance is no different than a climb via/descend via clearance except ATC provides a new top altitude or bottom altitude. All other published speed and altitude restrictions before the new ATC-assigned top or bottom altitude are still applicable.
Climb and maintain or descend and maintain (unrestricted): Pilot is expected to vacate current altitude and commence an unrestricted climb/descent to comply with clearance. For aircraft already climbing via a SID or descending via a STAR, published altitude restrictions are deleted unless reissued by ATC. Speed restrictions always remain in effect unless the controller explicitly cancels or amends the speed restriction. Likewise, pilots are expected to fly the lateral path of the procedure.
Speed phraseology: Absent of any qualifying instructions, issuance of a climb or descend via clearance cancels a previously issued ATC speed adjustment and provides pilot discretion to adjust speed while requiring compliance with upcoming restrictions.
Published speed restrictions (constraints) may be applicable to a specific fix (for example, BRBBQ at 280 knots) or the entire procedure (for example, “Turbojet aircraft descend via Mach number until intercepting 280 knots. Maintain 280 knots until slowed by STAR”); the latter restrictions are found boxed in magenta underneath the procedure’s title/name on Jeppesen charts. Qualifying instructions may include specific ATC instructions to maintain an assigned speed until passing a defined fix (waypoint) and then complying with the subsequent published speed restrictions.
Resume normal speed: Cancels ATC-issued speed restrictions and instructs the pilot to return to normal aircraft speed where no restrictions are published on the procedure/route currently being flown. It does not delete published speed restrictions on upcoming segments of flight.
Resume published speed: Cancels ATC-issued speed restrictions; pilot is expected to comply with speeds published on SID/STAR.
Delete speed restrictions: Cancels ATC-assigned and all published speed restrictions on charted procedure. This clearance often is conditional, deleting speed restrictions to a named fix (waypoint) and then resuming the published speeds on the remainder of the SID/STAR.
Lateral or course deviations: Pilots must use caution and insert the proper SID/STAR transitions into the flight management system. ATC clearances will include specific SID transitions (for example, TBIRD5.MATLK) or STAR transitions (for example, ROKKT.CPTAN3) to include runway transitions.
In addition, an ATC clearance to laterally deviate off a published SID or STAR for weather deletes the speed and altitude restrictions. However, “expect” to be re-cleared direct to a point on the procedure and resume the subsequent airspeed and altitude restrictions on the SID or STAR.
Pilot/controller phraseology: Accordingly, pilots shall respond to “climb via” or “descend via” clearances by repeating the clearance verbatim. Phrases such as “climbing on the SID” or “on the arrival” are not acceptable and create additional workload on the controller.
Acceptable examples include:
“Falcon Five Bravo Sierra leaving two thousand, climbing via the CRNKY Two, expect to maintain one two thousand (12,000).”
“Gulfstream One Two Three Alpha Lima, leaving one six thousand (16,000,) descending via the SNRKY One arrival landing south.”
The guidance when changing frequencies or on initial contact is to advise ATC of current altitude, “climbing/descending via” procedure name, and runway transitions as assigned. Sounding professional on the radio is part of your or your company’s brand (note: cat meowing noises on guard is neither impressive nor professional).
Avoiding Errors
Pilots can avoid errors (deviations) when flying an RNAV SID or STAR by adhering to company or manufacturer procedures.
In general, these procedures include loading (inserting) the correct runway, procedure (SID or STAR), and transition into the FMS. For the arrival phase, look to see if the RNAV STAR “connects” to an instrument approach procedure.
Thoroughly review the published procedure to include all airspeed and altitude restrictions. These restrictions are nuanced, as an example an airspeed may be preceded by “at,” “expect,” or max/min.” Whereas altitude restrictions may be listed as a hard “at” altitude or a range of altitudes (“at or above,” at or below,” etc.). Also, as mentioned earlier, look for the magenta box (on Jeppesen charts) underneath the chart title that may have a mandatory speed restriction; this is one of the most overlooked items by pilots.
Next, with your copilot, cross-check and compare each waypoint and restriction on the FMS legs page(s) to the published RNAV SID or STAR. This step seems cumbersome, but it’s well worth it!
Once the FMS waypoints (as coded) match the published procedure, brief and discuss the SID or STAR and how you plan to manage the vertical path and any speed restrictions. If there is a speed restriction that is applicable to the whole procedure (the magenta box), can you modify the speed on the PERF/Climb or PERF/Descent page to make that transition easier? Also, be aware of the effects that tailwinds and engine anti-ice (as an example) may have on the descent profile.
High-performing crews accomplish thorough briefings that not only include how the procedure will be flown, but also discuss contingencies such as how to manage the vertical path and speed if the track mileage is reduced when turned off the arrival.
Hopefully, this discussion stimulates some conversations on how best to fly RNAV SIDs and STARs and avoid some of the common “gotchas” that confuse pilots. To gain a mastery level of understanding on this topic, it is highly recommended to read the NBAA’s Domestic Operations Committee “briefing” on climb via, descend via, and speed adjustments—it is very well written and should be considered a must-read for any pilot operating in the National Airspace System.
The opinions expressed in this column are those of the author and are not necessarily endorsed by AIN Media Group.