Maintain High Speed

[Wings of Arabia]

Recently, in the vicinity of a class C airspace, we were doing the usual 250kts below 10K when we were instructed to maintain high speed as we were vectored on the downwind, when ATC asked us to maintain high speed, he didn’t seem happy with the 250kts, or so we thought, so we maintained 280kts as long as possible in anticipation of the base leg. The question now is, when pilots are asked to maintain high speed, what exactly are they supposed to do? Or how fast are they supposed to go?
Thanks

[AirNoServicesAustralia]

Its all about the intent of the instruction. If we ask for high speed we are trying to get you in as fast as we can to keep the sequence moving. So with that in mind I would expect that you would give us whatever you can that is safely within your aircraft and your capabilities. If ever in doubt ask for example "is 280 kts enough", if it isn't then the controller may go for plan B as one of the other guys may be able to go faster and the sequence may work better. Its all about the greater good, as even though it may surprise some pilots we don't care who is number one or number last, as it is all about getting the job done as efficiently and to be honest as easily as we can. Cheers :ok:

[Dogma]

Sounds good - one heads up for the ATCOs - Our low cost index makes the "high-speed" decent phase blockout at a wooping 260kts.

Save fuel - stick to the cost index decent speeds!

[TinPusher]

Maintain high speed = fly the 'clacker'!!!!
Forget about saving the gas as the alternative may well involve burning the same gas in a holding pattern or being slowed right up (high drag config) and still burning gas.
Sounds good - one heads up for the ATCOs - Our low cost index makes the "high-speed" decent phase blockout at a wooping 260kts.
Save fuel - stick to the cost index decent speeds!
As ANSA says we are more interested in the greater good and by one pilot worrying about his 'cost index descent speed' may well involve us then having to screw with number 2,3,4,5 and 6's 'cost index speed' so the 'systems' cost index gets screwed.

[HEATHROW DIRECTOR]

Shouldn't the instruction be either "No ATC speed restriction", or a specified speed?

[TinPusher]

Shouldn't the instruction be either "No ATC speed restriction", or a specified speed?
Yes it should!:D

[ADIS5000]

Can't believe it but I'm going to disagree with HD!!! .... Sorry!!

My understanding is that (in the UK) the phrase 'no ATC speed restriction' means the pilot may fly at up to 250kts IAS below FL100 and then no limit at and above FL100. The rationale behind this being that the 250kts below FL100 rule is the Air Navigation Order's restriction (ie a legal requirement) which (when routing is towards or in Class G) cannot be lifted by ATC. If inside and remaining inside CAS then the phrase should be 'cleared high speed', ie: specifically lifting the ANO imposed speed limit which is permitted when remaining inside CAS.

Regards, ADIS

[No Further Requirements]

Don't companies have their own procedures about the maximum an aircraft can do at different levels? I know when I ask for max speed, I stipulate above and below 10,000. What I am looking for from the crew is as fast as possible for as long as possible - there are no restrictions apart from your own company's or from the aircraft manufacturer!

Max speed = warp factor 5 please! If I wanted a particular speed, I'd ask for it.

Cheers,

NFR.

[AirNoServicesAustralia]

The reason "maintain high speed" is often used, especially when a little higher and further out is because as an ATC I can't possibly know all the individual aircraft speed restrictions and limitations there might be (eg. cracked windscreen, or just that pilots are not familiar with the arrival etc.), so I ask an aircraft to maintain 300 kts and best case he has to tell me he can't do it because "blah blah blah" or worst case he follows ATC instruction above all else (especially common with pilots from the old Eastern Bloc) and he places his aircraft in danger. Better to ask for high speed and watch the radar g/s and if in doubt then ask what speed is.

Plenty of ways to skin a cat. This is just one of them.

[anotherthing]

HD is correct in this one... if you tell an A/C to maintain high speed because you are basing sequencing on it doing so, what speed do you specify for number 2 or 3? You need to know that speed to apply speed control! For further proof of this read what Dogma says!!

One pilots 'high speed' might be another pilots low cost index descent speed!

Dogma I don't know which airline you work for (be helpful if you told us so we knew the company SOPs), but I recently had a pilot who I said 'no ATC speed restriction to' and he seemed to decelerate.... as it was quiet I asked him if he had done so and he replied that it was new company SOPs... but he added that it was also written into them that if ATC instructed him to fly a speed higher than his low cost descent speed, then he was to disregard the slow descent to comply.

ADIS5000 - in the LTMA, if any of us ATCOs told an A/C below FL100 that there was no ATC speed restriction, we would expect him to accelerate above 250kts, totally the opposite of what you are saying!!

I've never heard the phrase 'cleared high speed'... seems like a locally made up phrase to me... "high speed approved" seems more in keeping with standard phraseology as releasing an a/c from a speed restriction is not technically a 'clearance'...

[PPRuNe Radar]

My understanding is that (in the UK) the phrase 'no ATC speed restriction' means the pilot may fly at up to 250kts IAS below FL100 and then no limit at and above FL100. The rationale behind this being that the 250kts below FL100 rule is the Air Navigation Order's restriction (ie a legal requirement) which (when routing is towards or in Class G) cannot be lifted by ATC.

Correct, but only if there had been a speed restriction of less than 250Kts issued in the first place. In all other cases in Class E, F, and G airspace, that's the legal limitation anyway, so why would any controller issue an instruction which actually changes nothing ??

If inside and remaining inside CAS then the phrase should be 'cleared high speed', ie: specifically lifting the ANO imposed speed limit which is permitted when remaining inside CAS.

It's not a phrase in the CAP413 though.

AIC 53/04 states that no 'ATC Speed Restriction' means that the pilot should operate his aircraft at a speed to ensure adequate obstacle clearance, to comply with his flight ops manual, to not predujice the 'see and avoid' principle, to comply with the limits for Classes E, F and G airspace, and to ensure adherence to NPRs and CDAs.

Ergo, if flying above 250Kts means that the pilot is still able to comply with the conditions above and ATC grant him 'No ATC Speed Restriction', then the pilot is free to accelerate above 250Kts. In airspace Classes A (but only where speed limits are published - e.g SIDs or STARs), B (which the UK no longer has), C, and D, the 'See and Avoid' principle is met by the known traffic environment.

HD is on the money :ok:

[chevvron]

Certain ex-military (but civil registered) aircraft have an exemption written on their permit to fly allowing them to exceed 250 kt when transitting (ie NOT displaying) in class E, F or G airspace below 10,000 ft (with certain caveats). Watch out for an ATSIN appearing soon!

[Petit Pompier]

"No ATC Speed Restricitions" or "No Approach Speed Requirements" (a term used Down Under) don't mean go as fast as possible, they only indicate to pilots that they can go faster than the 250kt below 10000ft restriction, if they feel like it. I only use it when there is no need for the speed restriction and any speed flown will not affect the sequence.

When I want a pilot to fly fast to make a sequence work, I prefer specifying a speed to a point (320kt to 15NM Final or 250kt to 5NM Final). In the event this is beyond the capabilities of the aircraft the pilot will soon tell me so, and I can go to plan B, or C. Some operators place additional restrictions on the operation of their aircraft that may come as a suprise when a speed and point aren't specified (eg not above 250kt below 5000ft or 210kt below 3000ft) these can make life interesting when the aircraft suddenly levels off thousands of feet above it's cleared descent level, so that it can wash off it's speed.

I don't favour the use of "Maintain High Speed" or similar phrases, as it tends to mean different things to different pilots.

PP

"Have a plan and make it work"

[CAP493]

My understanding is that (in the UK) the phrase 'no ATC speed restriction' means the pilot may fly at up to 250kts IAS below FL100 and then no limit at and above FL100....
Most UK civil ATCOs issuing this advice inside controlled airspace Class A, do so on the basis of lifting either the 250 kt below FL100 speed restriction on departure or alternatively, removing the need to comply with the published STAR speed limit points on arrival. In neither case does it remove any responsibility from the flight deck to comply with the SID tracks or to operate the aircraft in an manner appropriate to the phase of flight at the time.


Many operators do in fact prescribe a maximum of 250 kt below FL100 inside and outside controlled airspace anyway.


The phrase "Maintain high speed" (although not detailed in the UK MATS Part 1) if used, really should be qualified with "...for as long as possible". or "...if able". The phrase "Keep your speed up" is not authorised for use, at least in the UK. :8 :8

[Neptune262]

If we ask you to maintain high speed we hope that you will do more than normal (i.e. more than the 250kts below 10,000ft) however if you actually asked us on the RT what that speed should be - a lot of us would have to say 250kts :-(

Basically it is a way for us to get you in quicker and bend some rules at the same time......do whatever you are comfortable with......if it doesn't work out we will sort it out using other means!!

[Wings of Arabia]

The reason I brought this up is because of that odd flight where bad vectoring was combined with high speed. An overshoot of the localizer occurred as a result. When I reported this overshoot to our operation, the safety pilot insisted that when ATC says “maintain high speed” he/she means maximum of 200kts/210kts. This didn’t make any sense to me since the normal speed in local AIP and our SOP manuals are 250kts below 10,000’ :confused:. It’s good to see how real controllers interpret and understand this phrase.
Thank you everyone :)

[Soft Altitude]

As someone rightfully mentioned: "Keep high speed" means different thing to different pilots.
If I am doing 300 Kts on descent, and am asked to keep high speed, I will definitely maintain 300 Kts or more, which comes in very handy in case of late descent clearance. Our SOP says that in any case we have to come back to 250 Kts at 5000 Ft AAL at latest !
One of my previous airlines I used to work for, allowed us to maintain more than 250 Kts, on ATC request, all the way down to 3000 Ft AAL !
Personaly I am strongly against low speed descents, if the vectoring is right, there is no point in maintaining whatever "low cost index" descent, be it on short or on long haul flights, It is not in the last 20 minutes of flight or so (during descent) at idle power most of the time, that you will save whatever fuel !