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If a controller clears me for a procedure, and also says "...do not exceed ___ knots", how long does that restriction apply for?

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  • $\begingroup$ Is your question referring to anytime a controller issues a speed restriction or only after a controller "clears" you for a specific procedure (such as an ILS approach, or similar)? Your headline question and your actual question do not make this distinction. (almost like you are asking two different questions) $\endgroup$
    – 757toga
    Jun 5, 2022 at 22:51
  • $\begingroup$ Which country are you asking about? Rules may vary. $\endgroup$
    – randomhead
    Jun 5, 2022 at 22:55
  • $\begingroup$ @757toga Both, I guess? Your answer is great though, thank you so much $\endgroup$ Jun 6, 2022 at 2:35
  • $\begingroup$ @randomhead I was asking about the US, I definitely should have put that in the question. $\endgroup$ Jun 6, 2022 at 2:36

2 Answers 2

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In the U.S., if you are assigned a speed restriction by ATC that restriction remains in place until you are "cleared" for a approach procedure (such as an ILS), receive a "climb via" or "descend via" clearance ( when flying SIDs or STARs), instructed to "resume normal speed" (or similar phraseology such as "delete speed restrictions," etc.) or given a different speed assignment/restriction.

If you are cleared for a procedure, such as an ILS approach, and are instructed to "do not exceed 150 kts" (for example from your question), this speed restriction is to be followed for the duration of the approach unless you are given a different speed assignment or instructed to (something like) "resume normal speed."

Also, keep in mind that if you are instructed to "maintain 270 kts" (for example) while above 10,000 ft (msl) and then instructed to descend below 10,000 ft., you are required to (without having to receive ATC authorization to do so) slow to 250 kts before descending below 10,000 ft. This same requirement (see [14 CFR 91.117]) regarding regulatory speed requirements, also has to be observed by the pilot while flying in other airspace areas that have specific speed requirements.

Additionally, there are circumstances where a published speed restriction is automatically canceled (such as when receiving a vector off of a SID/STAR for some reason).

To have a more complete and comprehensive understanding of the subject of your question, the Aeronautical Information Manual (AIM), section 4-4-12, Speed Adjustments, contains an explanation of the ATC/Pilot requirements pertaining to speed assignments. This would be an important reference for you to read and understand.

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  • $\begingroup$ Assigned speeds are not supposed to apply within the FAF or a five-mile final. When assigning a speed in conjunction with an approach clearance (because absent such an instruction, the approach clearance automatically deletes speed restrictions) ATC is supposed to phrase the instruction so that it only applies until the FAF or a five-mile final. $\endgroup$
    – randomhead
    Jun 6, 2022 at 15:48
  • $\begingroup$ @randomhead - that is an ATC responsibility not to assign a speed adjustment inside the final approach fix on final or a point 5 miles from the runway, whichever is closer to the runway. Should not be an issue that the pilot needs to be aware of. $\endgroup$
    – 757toga
    Jun 6, 2022 at 16:15
  • $\begingroup$ Just mentioning it because you said a speed assigned along with an approach clearance applies for the entire approach. That could work for a "do not exceed XXX knots" instruction, but not for a "maintain XXX knots" instruction. Pilots should be aware that they can speak up if necessary, should they ever get such an instruction. $\endgroup$
    – randomhead
    Jun 6, 2022 at 16:33
  • $\begingroup$ @randomhead Well, not to grind this point too fine, but the procedures (not me) say that the speed assignment (in the circumstance asked specifically by the OP) would apply for the duration of the approach unless canceled (procedurally or by phraseology) by ATC. Of course if "any" speed assignment is unacceptable to the pilot he/she should advise ATC. $\endgroup$
    – 757toga
    Jun 6, 2022 at 16:41
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You must maintain that speed until ATC releases you from that restriction. When ATC want you to do something, there's a good reason for it, so we do as we are told. However, if you think they may have forgotten you, you can always ask

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