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Sometimes I see SIDs with a long straight climb segment (say 10 nm), followed by a wide turn with an IAS constraint (e.g. MAX 210 KIAS).

Is there any issue in accelerating to 250 KIAS and then decelerating shortly before the turn? Is that ever done?

EDIT
Fictitious example:

enter image description here


EDIT #2
Here's the actual chart (I hope no copyright infringement):

enter image description here

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    $\begingroup$ Can you provide an example so we can look at the plate? Thanks. $\endgroup$ – ymb1 Sep 10 '18 at 15:22
  • $\begingroup$ I'm referring to LIPY, but I'm not able to find a link w/o a registration (I fear that I cannot post the chart). I add another chart in my post with an example. $\endgroup$ – Cristiano Sep 10 '18 at 16:34
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There is another limitation apart from the 250/10,000 one, according to ICAO Annex 11 Chapter 5 Appendix 4:

Speed limitations applicable to both IFR and VFR aircraft:
— 250 knots below 10 000 ft ASL; and
— 200 knots below 3 000 ft AGL within 10 NM of a controlled airport.

So within 10 NM and below 3,000 ft AGL of the controlled airport, you are not supposed to exceed 200 knots.

Note: In the Rome example before the 210 knots PRA turn, the leg is 4+10+6 (20) NM, but all of it is still within (or very close to) 10 NM of the airport. Also note the 'at 3,000 ft' point, which is still below 3,000 feet AGL, so it's hard to justify trying to accelerate after that only to slow down again in 6 NM while climbing to 'at or above 6,000 ft'.


I checked the Italian AIP for any differences from the above ICAO limitation. AIP GEN 1.7 refers to Commission Implementing Regulation (EU) No 923/2012, in which no differences from Chapter 5 are listed, which is to say the quotation above applies in Italy.


What if it's more than 10 NM from the airport?

In this case the procedure design group (PDG) that designs the procedures will typically make any speed restriction clear.

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    $\begingroup$ You're going to be climbing in speed mode after leaving the OST 097 redial fix at 200 kts/3000 ft and you would never crank the speed bug to 250 kt then suddenly dial it back to 210, with only 6 miles/<2minutes to speed up and then slow down again. You will just dial it to 210, or maybe leave it at 200kt, until leaving the turn with the restriction. $\endgroup$ – John K Sep 10 '18 at 19:12
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The usual chart verbiage is, “do not exceed 210 KIAS until passing FIXXX”. That precludes speeding up and then slowing down.

While doing that & then slowing for the turn would probably maintain obstacle clearance (by keeping the turn radius to an expected value), you might compress with traffic ahead that is flying the expected profile. Also, some departures direct the slower speed to keep you climbing and minimize the noise impact to houses along the departure route.

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  • $\begingroup$ Please, take a look at the EDIT #2 for the actual speed restriction. $\endgroup$ – Cristiano Sep 10 '18 at 18:48
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    $\begingroup$ @Cristiano The distance shown in your example isn't enough for much of anything without an afterburner to climb to about 3,000' AND accelerate to 250 knots and then to slow back to 210. An F-15 probably could... but, why? In normal operations, what you suggest isn't done, at least in any departure I've ever seen. $\endgroup$ – Ralph J Sep 11 '18 at 6:59

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