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Speed Management/ Cruising Level

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Speed Management/ Cruising Level

Old 30th Dec 2020, 22:40
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Speed Management/ Cruising Level

Hi everyone,
I am wondering about pilot's preferences on speed restrictions . Let's say there's an aircraft (A320) at flight 360, cruising at M.74. Just behind him, there's another A320 climbing which has the same route and requesting FL360 while intending to take M.79. In this case, if my workload allows it, I ask the second one if he prefers to climb at FL360 with a speed restriction at M.74 maximum or if he'd rather stay at FL340 with no speed restriction. I've always felt like pilot prefer to fly without speed restriction, especially if the counterpart is a variation of altitude of 2000ft but what do they really prefer? Does it depend on each case/airline or is there some general rule that may apply? Is finding some middle ground (M.77 for both) a better solution?
Thanks !

Last edited by Shamrock2; 30th Dec 2020 at 22:55.
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Old 30th Dec 2020, 23:03
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I would always offer the 2nd aircraft the choice of FL with or without speed restriction.
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Old 30th Dec 2020, 23:07
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So in my example, you ask the 2nd if he prefers FL 360 with M74max or FL340 without speed restriction? Or do you try to suggest a higher speed for the first one?
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Old 30th Dec 2020, 23:59
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Similar aircraft would typically follow the restriction and keep their optimum flight level. The required mach adjustment cannot be that penalizing. Your example would be 78 - 76 with narrowbody Airbii in real life.

For different aircraft with larger gaps around .05 M the altitude trade becomes interesting. 2 above or 2 below is 4000. The winds could be quite different and that should enter the crew's choice. As well as what happens next, tactically. For instance, when going to the Canaries in peak summer, lower and faster is the preferred solution to skip the queue even if burning little more.

my 2p.
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Old 31st Dec 2020, 02:36
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I would say the general thought process of our lot (assuming the speed restriction isn't going to make us too fast or slow for comfort) would be to accept a level with a speed restriction if it kept us fast, or to take the lower level if the higher level would keep us slow. Maybe not so much if it's ~0.1-2 different from our requested, but I think most I work with would accept 2000' lower to take .79 over .74.
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Old 31st Dec 2020, 22:09
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It depends on the length of flight. 4 hours of going faster/slower than optimum is very different than an hour or so. Fortunately most traffic is at pretty much similar speed nowadays not like a B733 @ FL350 @ .75 chased by a [email protected] that we had a few years ago.
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Old 31st Dec 2020, 22:28
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The Classic was pushing it!
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Old 1st Jan 2021, 17:42
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Originally Posted by FlightDetent View Post
The Classic was pushing it!
OK how about .73?
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Old 2nd Jan 2021, 10:17
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Stick them on headings and allow to overtake? (Sorry, stupid approach controller here).
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Old 2nd Jan 2021, 10:46
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Originally Posted by mike current View Post
Stick them on headings and allow to overtake? (Sorry, stupid approach controller here).
Typical approach attitude!! lol Many LOAs between units require a minimum distance at the same FL.

Last edited by 250 kts; 2nd Jan 2021 at 14:25.
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Old 2nd Jan 2021, 17:18
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Originally Posted by 250 kts View Post
Typical approach attitude!! lol Many LOAs between units require a minimum distance at the same FL.
Fair enough. Seems sensible
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Old 2nd Jan 2021, 18:19
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Only half a speed-brake
 
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SLOP downwind for the heavy, 71 and. 82. Call me back when ready with your request to maintain own separation. Next ensuing report in 15 minutes.
(sorry, slightly wet dreaming pilot here).


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Old 3rd Jan 2021, 23:11
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My two cents: I would ask the slower ACF what increase in Mach # would he accept for spacing, and would offer that new Mach # to the second ACF. If he's happy with it, he will fly at F360. If I have the time, I also check their routes to see for how long the restriction would have to last.
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Old 7th Jan 2021, 01:54
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"Unavailable due traffic" - really though I would offer it but with the speed restriction. Normally however there's something better you can do like ask the guy in front if he wants a better direct, if he wants to speed up, or wants a different level. Then you're in the clear for the guy behind to level change without watching a tight gap.

In my experience pilots jump at the oppurtunity to speed up "yes sir any speed you want!", due to being limited to flying slowly due cost index calculations by the bean counters below. The newer A350's, 787's are brilliant for doing M0.86 or greater for spacing, they jump at it when we ask.
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Old 7th Jan 2021, 12:37
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Originally Posted by Speed_Alive_V1 View Post
In my experience pilots jump at the opportunity to speed up "yes sir any speed you want!", due to being limited to flying slowly due cost index calculations by the bean counters below. The newer A350's, 787's are brilliant for doing M0.86 or greater for spacing, they jump at it when we ask.
I always crack a smile when Ryanair pilots (who spend their lives restricted to a snails pace of 243kts) check in and ask with their best puppy dog eyes/pretty please voice if there's any speed control. Essentially begging us to speed them up.

Depends what mood I'm in as to whether I 'help'
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Old 8th Jan 2021, 09:35
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Heathrow departures

Not FR but SR..early days of 250 knots departures were obliging to allow VNE to pass under Biggin stack which would knock a couple of minutes off our flight time.
Fokker 100 was a pain (thick wing no droop) as didnít cruise at Mach .8 +, the Scandinavians soon got fed up, kept us low and out of the way.
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Old 16th Jan 2021, 09:18
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Originally Posted by mike current View Post
Fair enough. Seems sensible
Don't mind the lazy ACC controllers, they're afraid they'll spill their coffee if they have to reach for the phone to make the coordination.
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Old 16th Jan 2021, 14:05
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Only half a speed-brake
 
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A couple of years ago a small group of ATCOs came to visit the SIM as a part of an educative assignment from the ANSP. Same age bracket as the two pilots we were, we made the most of it in a very clever and supportive atmosphere. RNAV and RVSM implementation had been the big thing around 5 years prior and a favourite examination subject when all of us received the ID badges for our respective parts of the airfield. Across the ranks we were keen and well educated on the subject, perhaps with some academic background too.

Given the local geography, typical morning departures from the capital would cross the national border at FL240 or continuous climb, having spent about 7 minutes with the lower ACC after leaving the TMA. I did not see the relevance of that when asking how would they deal with an air data sensor fault and UNABLE RVSM call from us at FL180 if there was a discrepancy during the required altimetry check.

Some lads at once opened their lips to start talking but awkwardly all remained silent for a small lull and then exhaled instead, before one of them after a little more contemplation came with a perfect answer.

I learned something about ATC that day.

Spoiler
 

Last edited by FlightDetent; 16th Jan 2021 at 14:15.
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