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The ATC issues "Cross BHAWK at FL240" initially. After few minutes, the ATC instructs "Descend Via FYTTE5 arrival". Should we comply with the crossing restriction at BHAWK, or the restriction can be omitted?

The JO 7110.65Y says

Clearance to “descent via” authorizes pilots:

  1. To descend at pilot discretion to meet published restrictions on a STAR.

and

“Climb via SID except after Baret, maintain flight level one niner zero.”

NOTE1. Considering the principle that the last ATC clearance issued has precedence over the previous, the phraseology “maintain (altitude)” alone cancels previously issued altitude restrictions, including SID/STAR altitude restrictions unless they are restated or modified, and authorizes an unrestricted climb or descent. Speed restrictions remain in effect unless the controller explicitly cancels the speed restrictions.

However, the example given in "descend via" does not say anything about "previous assigned crossing altitude." And the note given in "climb via" example only explains the phraseology "maintain" would cancel previously issued altitude.

Is there any FAA document stating the altitude restrictions assigned previously can be omitted or still valid, after getting "descend via" clearance?

KORD FYTTE5 arrival

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    $\begingroup$ If in doubt, there's no doubt: ask ATC for clarification. $\endgroup$ – DeltaLima Jun 19 at 8:23
  • $\begingroup$ Since the STAR lists an upper limit at BHAWK of FL260 and a lower limit of FL220 there's no reason you couldn't comply with the clearance to cross at FL240. And in systems I'm familiar with, if you load the STAR in your FMS with VNAV engaged it will plan your crossing of BHAWK at FL240 (half way between the limits.) $\endgroup$ – Gerry Jun 19 at 12:44
  • $\begingroup$ @Gerry That isn't universal; the 737 FMC will stay as high as possible as long as possible for fuel efficiency, so if being at 260 at BHAWK doesn't create a problem for later restrictions, that's what it will do if the pilot didn't overwrite the 260-220 altitude with the first "at 240" clearance. $\endgroup$ – Ralph J Jun 19 at 13:27
  • $\begingroup$ @RalphJ You are correct. There's a lot of variability between systems. Where it gets interesting is with the multiple crossing restrictions. The FMS (per the current MOPS) will try to maintain a constant vertical path angle between restrictions. In the above, since FYTTE is a cross at 11000 it will try to straight line the vertical path between BHAWK and FYTTE as long as it meets the restrictions on the intermediate waypoints. $\endgroup$ – Gerry Jun 19 at 14:11
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The restriction to cross "BHAWK at FL240" is overridden by the controllers latest clearance to "Descend Via FYTTE5 arrival", unless they include the instruction descend via "EXCEPT MAINTAIN FL240".

FAA Climb Via/Descend Via Speed Clearances Frequently Asked Questions, page 6, questions 8.

If unsure, you should query ATC though.

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  • $\begingroup$ Or, "cross BHAWK at FL 240 and then descend via..." might be the way they'd assign that. But that is certainly not the same as just "descend via," which does cancel the "at 240" clearance unless it's restated. Definitely worth considering asking, "so understand you don't need BHAWK at 240." $\endgroup$ – Ralph J Jun 19 at 13:33
  • $\begingroup$ And, welcome to AV.SE, by the way! $\endgroup$ – Ralph J Jun 19 at 13:33
  • $\begingroup$ Thanks so much! Yes “Descend Via” clearances require a careful watch. There is certainly a significant threat of altitude bust. On the Airbus, for example, it would be easy to take a heading for traffic and then get cleared back on the arrival but if you didn’t check the modes you would still be in “open descent” which would not comply with any restrictions on the way down to the altitude set in the FCU. $\endgroup$ – AviationMatters Jun 19 at 14:15
  • $\begingroup$ Just wondering which publication says "descend via STAR" would cancel previous assigned restrictions. $\endgroup$ – benck Jun 19 at 17:00
  • $\begingroup$ no problem we are cleared descend to the bottom altitude of the STAR, but the FAQ does not answer "descend via STAR" would cancel previous assigned restrictions or not. $\endgroup$ – benck Jun 19 at 17:12
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In JO 7110.65, 4−2−5. ROUTE OR ALTITUDE AMENDMENTS. b. When route or altitude in a previously issued clearance is amended, restate all applicable altitude restrictions.

The example given:

“Amend altitude. Cross Ollis intersection at or above Three Thousand; cross Gordonsville V−O−R at or above One Two Thousand; maintain Flight Level Two Four Zero.”

(Shortly after departure, altitude restrictions are no longer applicable, the controller issues an amended clearance as follows):

“Climb and maintain Flight Level Two Four Zero.”

When issuing an amended altitude (cross BHAWK at FL240 >>> Descend via STAR to bottom altitude), ATC should restate all altitude restrictions if applicable. If not restated, it's no longer needed.

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