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I just took the instrument knowledge test and one of the questions referred to this STAR. Like many of the questions, there were two right answers and you were supposed to pick the one that was most right.

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(airnav)

The question stated that you were cleared for the STELA ONE arrival from the west and asked what altitude you should be at when crossing STELA. My understanding of a clearance for a STAR is that, unless otherwise instructed, you should use both the lateral and vertical guidance on the chart. So at STELA, you should be at 11000'. The notation for expect isn’t applicable unless you were told to fly at a higher altitude when given your clearance. Even then, you wouldn’t descend to 11000' until instructed.

Is my understanding correct, or am I missing something?

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  • $\begingroup$ The exact wording of the question / clearance would be very helpful in order to give an accurate answer... $\endgroup$ – Lnafziger Apr 24 '17 at 20:57
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    $\begingroup$ "Expect" is just that......"expect". Usually the "expected" happens, but not always. My understanding is they are for planning purpose only. The actual altitude you fly would depend on any clearance or instructions received. $\endgroup$ – kevin Apr 24 '17 at 20:58
  • $\begingroup$ @Lnafziger I think I quoted the question exactly. I don‘t remember the exact wording of the answers. I can’t find the question in the latest Gleim book and it is not in my database of previous questions, so I don’t know what the exact wording of the answers was. Two of the answers said to cross STELA ONE at 11,000. I think the wrong one said to descend to 11000 at STELA ONE while the correct one said to follow the charted procedure. $\endgroup$ – JScarry Apr 24 '17 at 21:20
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Terrible question (not your question, but the test question).

As far as I can tell, there are NO altitudes on the arrival that are mandatory; everything is an "expect" altitude only.

When you are "cleared for the STELA ONE arrival", you are cleared to (required to) fly the lateral ground track, and comply with any airspeeds stated on the chart ("cross at xxx knots", not "expect to cross at xxx knots" restrictions). That clearance by itself doesn't clear you for any altitudes, even ones that are mandatory on the chart.

When you are cleared to "Descend Via the STELA ONE" arrival, then you are additionally cleared for all mandatory altitudes. (Which I don't see any of on this chart, but I may have missed one -- NOS formatting isn't the best.) Importantly, if the arrival has published altitudes to cross A at or above FL 230, cross B at or below FL 200, cross C at 12,000', and expect to cross D at 5000' (and no other altitudes after D), then you are ONLY cleared down to 12,000' -- you are NOT, in that case, cleared for the 5000' altitude. You can expect it (i.e. load it in the FMC), but you can't depart 12,000' without explicit ATC clearance (i.e. don't spin the 5000' into the altitude window on the mode control panel until ATC says "cross D at 5000").

Yeah, it's a "gotcha". Really poor human factors design for an arrival to do that, IMHO, but there are a few of those out there.

Now, flying the STELA ONE, you're PROBABLY going to end up crossing STELA at 11,000', but until they assign you that altitude, you aren't cleared to do so. "Expect" altitudes on an arrival have to be explicitly given by ATC -- "Descend Via" doesn't include those.

I don't know what other answers you had on the knowledge test besides 11,000', but my first guess would be that something along the lines of "not enough information given to know" or "cannot be determined" or "last assigned" would be better than "11,000" if the question asked something along the lines of, "having been assigned this arrival, at what altitude are you cleared to cross the STELA waypoint?" With only clearance for the arrival itself, you haven't been cleared for ANY altitude change.

I don't much like that arrival since it has no mandatory altitudes at all, and I really don't like that question. Have to love the FAA, sometimes!

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  • $\begingroup$ "descend via" isn't really part of this question and kind of clouds / confuses the issue here.... $\endgroup$ – Lnafziger Apr 24 '17 at 21:01
  • $\begingroup$ @Lnafziger It seems relevant in that in the absence of Descent Via, you aren't cleared for the published altitudes, even the mandatory ones. As you point out, such a clearance wouldn't be appropriate here anyway. But being cleared for the STELA1 arrival, you're 0 for 2 in terms of ways that you could cross STELA at 11,000... you aren't cleared to descent via, and an expect isn't a clearance anyway. $\endgroup$ – Ralph J Apr 24 '17 at 22:30
  • $\begingroup$ All I was suggesting is that since there was no mention of "Descend Via", explaining how it would work isn't necessary and could confuse the issue. Especially since you refer to "when given a descend via on the STELLA ONE arrival" which isn't something that should happen.... Removing that would make it more clear. Anyway, just a suggestion! $\endgroup$ – Lnafziger Apr 25 '17 at 21:41
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If you're given a Descend Via, then you use the STAR for vertical guidance, and usually those clearances are given on RNAV STARs. Otherwise, you'll be given explicit descent instructions the Expect is just a planning tool, such that you can be prepared if you're given, for example a Descend Pilots Discretion, cross STELLA at 11,000, or some other variation and plan ahead for your descents.

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The exact wording of the arrival clearance is critical in order to properly answer your question.

Since this arrival only contains "expect" altitude restrictions, the clearance should also contain a vertical clearance (controllers are not supposed to give "descend via" clearances for arrivals which only have "expect" altitude restrictions).

If no vertical clearance was given along with the arrival, then you must comply with the previously issued altitude clearance, and you may not descend to comply with the altitudes published on the chart until you have been specifically cleared to do so. I believe that is the whole point of the question.

In this situation, I would still keep track of what is needed in order to make the published restriction, and if it starts getting close query ATC to see if they want me to cross it. This just helps to keep me from getting "slam dunked" and needing an excessive descent rate if they "forgot" about me for a few minutes.

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  • $\begingroup$ I haven’t flown any STARs, and can’t find anything in the FAA docs about how to descend, but on the NBAA website they say "Climb via” and “descend via” are abbreviated ATC clearances that require compliance with the procedure's lateral path, associated speed restrictions, and altitude restrictions published on the SID or STAR. " nbaa.org/ops/cns/pbn/climb-via Your answer seems to conflict with the NBAA guidance. Are you saying that in the real world, the published altitudes are not followed and that you will always be given an altitude when flying the STAR? $\endgroup$ – JScarry Apr 24 '17 at 21:34
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    $\begingroup$ @JScarry No, Lnafziger & the NBAA are consistent here. IF they cleared you to descend via (and not just cleared the arrival), then you'd be cleared for the mandatory altitudes, but not the "expect" altitudes. They will usually assign you those altitudes that the STAR tells you to expect, but until they do, you aren't cleared for them. $\endgroup$ – Ralph J Apr 24 '17 at 22:32
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    $\begingroup$ @jscarry Absolutely. However, there was no mention of "Descend Via" in the question..... $\endgroup$ – Lnafziger Apr 25 '17 at 21:38

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