Pilot/Controller Responsibility in a STAR

When a descent clearance via a STAR is given by a controller, it is my understanding that adhering to the demands of the STAR is a joint responsibility- the pilot must fly the STAR and the controller must give the altitude clearances in a timely fashion. The majority of the times this works but on more than one occasion, controller clearance to descend below a certain altitude was late in a situation where a very steep descent is involved past a waypoint. I had this situation today at TJSJ. I was able to decelerate sufficiently to be able to land but it was ugly. So here are my questions:

  • Are controllers aware of the demands of a STAR specific to its vertical navigation path or is it exclusively a pilot’s responsibility to notify the controller that a very timely clearance is needed to descend further at a particular waypoint ?

  • If it’s the pilot’s responsibility, at what point is this request made ? Any suggestions or requirements on the appropriate language for making such a request ? Any other suggestions ?


The capabilities of an aircraft’s rate of descend varies in a number of ways e.g. headwind/tail wind, so if you feel you need to descend earlier you can allways request further descend. SImply stating: “Scandinavian 901 requesting further descend”.
The controller will usually give descend instruction based on his experience or LOA (Letter of agreement) with other controllers. If you request descend “too early” the controller might need to coordinate with others controllers before he releases you for descend. Also other traffic can be an issue and delay the descend clearence to you.

I love it when ATC “Descend via the STAR!” It retains altitude profiles and limits Radio traffic.

Surely, if a controller issues instructions to you that deviate from the STAR, you are required to conform to those instructions for everybody’s safety. Otherwise, what would be the reason for ATC :question:

Real world: if ATC forgets about us on a STAR and late descent instructions are issued, I will not dive like a maniac to make the next vertical constraint. ATCOs cannot expect this to happen, especially for passenger comfort. When I am on a ferry-flight (no passengers), I don’t mind diving at 6,000 feet/minute, but on a revenue flight this is not going to happen.
If you mess up, deal with the mess. Not a big thing. Many STAR-constraints are only for airspace structure and as such it is not a big deal if you don’t cross those points at the published level/altitude, IF ATC forgot to or simply did not issue you a descent clearance. They are aware of this, they do not expect us to do a “Stuka-dive”.

One more shocking fact: IRL it happens on a regular basis that ATC does not issue STAR-clearances altogether - they somehow expect to work with professional crews who know how to select the correct STAR. If not: that is the problem of the ATCO, not mine as a pilot!

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I was taught when I did ATC that if you need a Lateral deviation from a published procedure then I say: “Cancel STAR, turn Left, HDG xxx!”

Then maybe; “turn right, direct FLAVR, rejoin ALBR1A own NAV!”

In some places seems they just add an instruction and expect pilot to know what is happening.

It depends on the country. In Europe you just continue on the previously instructed STAR if ATC sends you directly to some point of that STAR. It’s logical, isn’t it?

OK, so asking/reminding the controller of descent needs does not violate any communication protocols. The problem in my post is particularly acute when a STAR has multiple steep descents. Since the B737-800 FMS is quite good at warning of upcoming steep descents, asking the controller for “further descent” when needed should not be a problem.
Thanks for the help.

If the steep descend is “build into” the STAR, I think it is a different matter - there must be a reason as to why it is build that way. In such a circumstance I’m not sure it is prudent to ask for descend outside the STAR - perhaps Andreas has info on this. It is a bit different than the need for descend due to reaching TOD.

No STAR should have a descent angle in excess of 3 degrees. That is the ICAO standard and is well achievable by all aircraft types.

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Andreas and Torben,

I agree with your comments 100% but your latest comments do not address the key question in my post. I never asked how to ask for a descent outside the STAR or doing anything else outside the STAR. My only question was TIMELINESS in providing further descents by the controller per the requirements of the STAR and the aircraft’s capabilities, i.e., what do I do if I I am expecting a further descent clearance and the controller has not provided it ?

I think you answered my question in your first reply, please let me know if otherwise.

Well, you ask the controller for it: “request further descent” would be the phrase for it. I personally don’t do it unless I really have to descend to make it to my destination at a stable and safe altitude, but if it is just about airspace structure I prefer staying high up in the sky as long as possible: I am fast (same IAS results in a higher TAS) and I burn less fuel.

Exactly, this is a “stable descent is in jeopardy” issue. The late further descent clearance is what caused the less than stable approach and my subsequent post but moving forward I know how to handle.
Thank you !

Yes, sure. In the end, if ATC could not descend you in time, ask for a few more miles (vector) to lose altitude. ATC cannot expect you to do stunts to make up for list distance.

There are freeware aircraft for some sims that are more slippery than an eel. Then if they throw in a speed restriction it can be impossible to meet the requirements. I find even a payWare A330 can be very hard to slow/descend.

As they are saying, Controllers can’t expect gold from aluminium, so Pilots just have to say “Unable next STAR Altitude!” Or similar.

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If the controller says something like “Descend with the STAR”, you don’t need to ask for descend for each leg of the star AFAIK. You simply do as described in the star.

Using the BOGET2 arrival into KLAX as example, the controller could simply clear you down to 6000’ by saying “United123, descend to 6000’, KLAX altimeter 29.92, descend with the star”. As long as you reach UPDOC at 6000’ and you’ve adhered to all the restrictions in the STAR, you should be good.
Perhaps not realistic to get the descend all the way down due to traffic, but anyways.

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In the US the controllers do not even have to issue an altitude/level for a STAR, they only say “Descend via … arrival” and will usually provide the local altimeter setting. Pilots are then authorized to descend via the STAR (lateral, vertical and speed constraints have to be respected) to lowest published altitude. in the example above that would be 6000ft at UPDOC. But you can also get cleared to an intermediate level/altitude only, cancelling any further descent clearance along the STAR.

The FAA website is quite nice listing all the examples, check it out: https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap5_section_4.html

:ok_hand: :+1: Very nice to have RW pilot input, thanks, Andreas

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Yes, very nice to have comments from a RW pilot and the interest shown to amateurs like me. I will definitely look at the FAA site. Here are some more specifics from my incident.

I am aware that there is no need to ask for descent in each leg of the STAR but in the incident that prompted this post, I was cruising at FL350 and the controller’s instruction was “American 2551, descend to 11000”. 11000 is a published altitude constraint in the STAR. The lowest published altitude in the STAR is 6000A. I reached 11000, no problem, and then did not receive a TIMELY further descent clearance, which led to an unstable approach and landing. I am concluding that in a situation such as I described, requesting further descent is still in order if one has not been provided, i.e., I could not have continued descending per the STAR’s published altitude constraints since the controller had cleared me only to 11000 within the STAR.

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Yes, you can ask for further descent. If a delayed descent instruction leads you into an unstable approach situation, ask for vectoring to provide more distance to lose height.

You are the PIC, you know what your plane can do and what you are willing to do. ATC is here to help and guide.