speed conrol request

[l39]

Hello everybody here.
I am an en-route controller from Eastern Europe. I’d appreciate if somebody tells me where to find an article or official document concerning speed adjustment techniques from the moment of changeover down to fl110 and the opposite- when an A/C is climbing, although it’s been written a lot here.
Also I have a few questions:
1.What if you want to reduce speed, when its still MACH, and shortly after you issue an instruction in IAS? I mean if there is a table indicating what MACH corresponds to certain IAS at a certain FL?
1. When the speed changeover occurs in descending, and what triggers it apart from COST INDEX?
2. What speed intervals the pilots may expect, after conversion to indicated, at different levels (let say from fl300 down to fl110)?
3. What standard and non standard phraseology do you use in this case?

Thank you in advance

[allrounder99]

Hi, at my work, we do have a table which describes Mach No to IAS at certain flight levels, but in all honesty, no one uses it. Because...

1. Different Aircraft/Airlines have different changeover levels that correspond to speeds, rather than specific Levels. Although I could imagine it being an airline Standard Operating procedure, to always make it say at level F250 for example. A particular aircraft however, standard climb profile, might for example, climb at 300KIAS until reaching M.80 and then continue to climb at M.80 until cruise. What level this transition happens is anyone's guess.

On descent, the reverse will happen, descend at M.80 until reaching 300KIAS and then descend at 300KIAS until speed reduction becomes necessary. ie FL110 perhaps.

Phraseology? "Report indicated Mach or IAS" and pick a number slower as you see necessary.

xxx123, reduce to 280 knots Indicated.

Hope this helps.

[On the beach]

Hi 139,

If you're using Mach No as a sequencing tool in initial descent, then as a rough guide ground speed = 10 X Mach No. So, Mach .86 (B747 high speed descent) = 8.6 NM per minute. On transition to IAS, 340kts (again B747 high speed descent) = 5.7 NM per minute. The difference being at lower levels the air is denser.

Forget tables, just use a specific Mach No. on descent into an IAS and leave it up to the individual pilots to do the transitioning. You will also find that M .86 is about the fastest that any airline will wish to commence descent and M .76 is about the slowest. Mach .80 into 300 kts is the average. Once transitioned and using IAS, then use a range of 340kts to 260kts down to the level where mandatory speed control for all aircraft starts (usually 250kts below 10,000ft).

Used correctly, Mach No into IAS descents can set up a nice in-trail sequence from top of descent to about FL110, if all your traffic is inbound from one direction. Top of descent to FL110 should be about 20 minutes, giving ample time to start sorting out a sequence.

On the beach

[l39]

Thank you colleagues ,
The information written above is useful to me. Appreciate sharing your experience.
And if there is a document/guidelines concerning speed control techniques will be glad to take a look on it.
Thanks again

[allrounder99]

Looks like On the beach has given you some good experience knowledge there.

He was talking mostly about Heavy jets with the speeds, and I agree with him on the numbers, Medium jets will be far slower for example, LOT's E170 and E190 often fly around in the low M.70's so try to get a feel for you traffic and its performance. No harm in asking pilots what works for them to learn what you are dealing with.

Good Luck.

[l39]

On the beach ,if I have to provide a reduced Mach No. into an IAS, if a speed reduction is required from top of descent. e.g. .86 into 340kts or 0.79 into xxx KIAS.(I don’t know the speed corresponding)
If I give him 290 KIAS on descent, it could actually be a mach/speed increase at upper levels.
I use : reduce mach .xx, and when convert to indicated, fly at xxx IAS. But I don’t know if I make him fly at a grater speed than he intended.
That’s why I needed that table..

[Sir Herbert Gussett]

l39, have a read of pages 385 to 389 here: http://www.caa.co.uk/docs/33/CAP493Part1corr.pdf