Applicability of Speed Restrictions - Arrivals

[JimGreen]

Hello ! Here is a subject which I have a question about...

An example (VIDP) of published speed restrictions for Arrivals specifies: -

250 kts below 10,000 feet
220 kts between 30 nm and 15 nm from VOR/NDB
Cat 'C' (e.g) : -
170 kts within 15 nm excluding final approach track
150 kts 10nm to 4nm on final approach track.

The speed of 170 kts on an Airbus A320 aircraft would require selection of Flaps 2 (at most weights), which has a direct and major consequence on fuel consumption.

In a usually crowded terminal area, the first instruction within 100 nm is "Reduce to minimum clean speed", which is fine.

My question is When does one change speed from 'BELOW 220' (which covers the minimum clean speed requirement) to 170 kts? Is it when the localiser interception is imminent ? or earlier ?

warm regards,

Jim Green

[roljoe]

Hi,

I have to admit that your question sounds quite ambiguous...!!!

When the atc ask me to reduce to min clean speed (like in LSZH)...I ackn..sying him..speed will be 160 kts...At this point he will say ok or reduce further...and I'll tx...not anymore min clean sir...and that's it..

So what's the point...??? min clean speed could be so different between ac type and model...

The real point is the controller wants to know about it..and then take further decision according to them in order to manage the traffics...

If 170 is ok for him..that's it..if 220 is to fast...he'll let you know...

and according to the weather condition..all this could be quite different..

that's where you have to know your perfo and needs..

[JimGreen]

Thank you Roljoe..I need an ATC perspective, which would include practical aspects faced by the Controllers.
I know what happens...
I need to know what SHOULD HAPPEN (from the Controllers perspective).

To clarify, it is most apparent is that: -
(1) A separation of 10nm between aircraft is noticeable initially which reduces to about 7.5 nm when the preceding aircraft is on the ILS.
(2) The ATC gives headings to maintain separations and increase/decrease distances and speeds are sometimes specified.

However, referring to published speed schedules, if as a pilot I reduced speed to 170 kts from the moment I was within 15 nm of the VOR, regardless of my sequence in landing (and like I said earlier, this would require a FLAPS 2 setting), my endurance would be reduced to reeaaalllly low veeerrrry quick.

Please note..Im speaking of high traffic density, where sequences of 18 and 20 are given by the ATC with approximately 2.5 min to 3 min intervals between landings.

[Canoehead]

In a busy terminal environment, you can forget about published speeds restrictions, for the simple reason that we will most likely assign you speeds. This speed should be maintained until you are cleared for the aproach, at which point more speeds will probably be assiged. The exception to that is the 250 kts below 10,000 on descent, which is often a regulaton which everyone must abide by.

As a very general guildeline, and if no speeds have been assigned, as you descend through 10,000 we expect 250 kts, then reducing to 210 abeam the airport on downwind, 180 kts on base.

However, as was mentioned earlier, our two main tools are vectors and speed controls. Most of us are very aware of the differences in fuel burn between no flaps, and flaps 2 at 160. We do take this into consideration, however, in order to provide precise spacing on the localizer our traffic must be low and slow. It is difficult to integrate aircraft on base at 230kts onto a 170 kt localizer. Once on final, speeds of from 190 to 160 are assigned to fine tune the spacing.

So if it's busy, the controller will invariably assign the speeds. Hope this helps.

[JimGreen]

Thank you Canoehead. Each time a flight is made to a known crowded terminal area, fuel planning becomes an issue.. holding times can be nil, or stretch to 45min..and scenarios change rapidly. But what I really admire is the ability of the controllers to predict and maintain (extremely) accurate approach times, which is what we need most.

Warm regards,

JG

[On the beach]

JimGreen

In this day and age generally,the faster you fly the final approach, the more aircraft can be landed per hour. I'm talking about 180kts to 4 mile final. After that point ATC should not ask for any speed - that's your bit. 180 to 4 is not always possible for some aircraft/airlines, I know, but it certainly ups the landing rate.

On the Beach

[JimGreen]

Thanks Beach, a thought springs to mind which is not exactly in line with this thread...
In the event of an incident (and subsequent investigation)...during landing..where would the 'published speed profile' stand vis a vis a different speed maintained on approach ?

Not always is a 'Reduce speed to ...kts or Increase speed to ... kts' ordered by the Controller, I observe it is more maintenance of a distance from the preceding aircraft which becomes a governing factor..

Regards,

JG

[loubylou]

Jim - unless you have been assigned a specific speed to fly then you can fly whatever speed you wish. But these days , generally in a busy TMA then you could expect to be given speed control - usually as Canoehead said - 210, then 180, then usually 160 kts until 4 nms. Inside 4 dme there should be no speed control issued.
OnABeach - not many jet aircraft are that happy to fly 180kts to 4 nms, and in a single runway operation - it doesn't really help with departures. In dual ops it doesn't help much either to be honest.

louby

[Quintilian]

I'm currently attending EPN ATS-academy in Sweden.

We have been told to use the following speed restrictions if needed (for jets):
250 kts or 230 kts (or MCL) until downwind/baseturn
180 kts on base leg
180 kts to 6 miles final, or
160 kts to 4 miles final.

On final minimum approach speed can also be used as a last resort (if one has ****** up properly)

[2.5 miles]

LHR:

Standard speeds;

250kts by DME 12 before hold VOR/DME
220kts within the hold and on Initial Approach
180kts on base leg and closing heading
160kts to 4DME (applied once appropriate final spacing is achieved)

Some leeway is applied for different speed requests.

On very windy days aircraft will be instructed to fly 180kts at an earlier stage, in order to control ground speed and limit turn radius so that aircraft fly a more conventional radar circuit shape and remain within confines of our radar manouvering area.

Within the London TMA we are currently running a survey on speed compliance, Mode S giving us a fairly clear indication! Twice in 3 minutes today, in strong winds with tight spacing critical (to maintain separation and respectable landing rate) aircraft took it upon themselves, on final approach to fly their own speeds. No major drama, but life made very difficult.

A request; I, and my colleagues understand the need to manage speed and energy, but PLEASE tell/ask us if you need to fly speeds other than we we have instructed, it saves paperwork! :ok:

[JimGreen]

I deeply appreciate the educative nature of your responses and thank you ALL for writing in.

'2.5 Miles' ....I'll do my best to keep my controller advised anytime I need a modification in the 'Prescription'.

Warm regards,

JG

[gulia]

In Delhi most of the domestic operators don't follow speed limit, they literally races with each other.When there is likelihood of traffic congestion we resort to min clean speed as to aircraft observe delay en route. Again no software, no ATM Flow management, only controller do it manually

[100m down/10,000m up]

Further on the speed issue - can somebody give me the answer on the following: let's say that STAR wants you to fly 250 kts from A to B and then 210 thereafter; halfway between A an B an air traffic control gives you speed restriction of 230 kts - does this apply to point B only (210 kts from there) or until you are given another speed instruction. Thanks.

[loubylou]

Once a controller gives you a speed to fly - then that overrides the star speeds, and you must fly what the controller instructs you to .
However - if the controller has not given you a reduction in speed and you need/want to reduce, then make that request - but please don't reduce speed until told to do so as this could conpromise vortex spacing behind you ( or indeed in front of you if you don't reduce when told to!)
Hope that helps

louby

[Kiltie]

Fully agree Louby in an efficient ATC environment but what about those radar controllers who give us an initial pattern speed of eg 210 and then turn us on to an intercept without mentioning speed again? Asking for permission to reduce would lead to extra RT clutter from dozens of aircraft in the same situation. On many occasions under radar control in UK zones I have taken it upon myself to revert to common sense and reduce because we are running out of track miles to slow the aeroplane down for a stabilised approach. Many radar controllers seem to instruct a speed to help their flow and then hand us over to tower with no mention of what the heck we are supposed to do with the last assigned speed! May I ask all controllers reading this to give us a DME limit for the speed instruction for want of an easier life?

[loubylou]

I agree the controller should then say something about the speed - but if they haven't, and it's busy - then you really ought to say something before randomly reducing speed yourself, if it's not busy then maybe you could just state that you are reducing!

louby

[clr4takeoff]

As soon as you're cleared for the approach it cancell any previous speed restriction, unless otherwise specified. Most of time we give a speed restriction with the approach clearance (160 to the FAF or whatever suit the localizer speed, the flow of aircraft on the loc). But if we don't mention any speed, it's at pilot discretion! :ok:

[loubylou]

The point you make had already been made in an earlier post

louby

[Kiltie]

"As soon as you're cleared for the approach it cancell any previous speed restriction, unless otherwise specified."

That's good to know. Is that another MATS reference hidden from us pilots? If someone had told me that years ago then I wouldn't have suffered the frustration for so long!

[2.5 miles]

"As soon as you're cleared for the approach it cancell any previous speed restriction, unless otherwise specified.

Unfortunately, I must disagree with this. We assign speeds to 4 DME and base separations on aircraft complying with those speeds. A clearance for the approach doesn't absolve the crew from maintaining speeds. If the crew require a different speed than assigned they should request it first (preferably before established on final approach with aircraft tight behind).

Point was made at LHR yesterday where a CSA 737 opted to fly at 140kts from 8 miles out, potentially causing aircraft behind to be sent around. However, the CSA was sent around, resulting in another 40 miles of fuel burn at 4A for non compliance. Following aircraft landed off the approach, after all why should he be penalised for complying.

[100m down/10,000m up]

loubylou and clear4takeoff

Do you have any reference for what you say?

Here is what I found in American Professional Pilot magazine: "After the STAR has been issued and accepted, any subsequent ATC changes to charted altitudes or speed restrictions does not cancel the remaining altitude or speed restrictions shown on the charted STAR procedure. Airspeed and altitude adjustments are commonly used during STARs to achieve traffic sequencing and separation."

Any coments from USA ATCOs?

[Kiltie]

2.5 miles; that's not what he's saying. NB his point "unless otherwise specified".

The CSA you mention failed to comply with the speed you had given him, ie you "otherwise specified" an approach speed to him.

What I would like to see is a CAA reference for the comment made.

[2.5 miles]

Kiltie

"As soon as you're cleared for the approach it cancell any previous speed restriction, unless otherwise specified."

Reading this again: If I clear the aircraft for the approach and do not specify a speed with that instruction, the implication is that the aircraft can fly its own speed!

I believe that where positive speed control is being applied, the last assigned speed is the one that should be flown "unless otherwise specified", anywhere outside 4DME. If, as is being suggested here, aircraft believe they can adopt there own speeds when cleared for the approach, it may explain why we have so many non compliance issues with our expectations. Is that the way pilots actually interpret "cleared for the approach"? This does raise another issue (no wish to hijack the thread), when a speed instruction is issued, what do flight crew consider to be an acceptable response time to act upon the instruction?

:)

[Kiltie]

2.5 miles

In the absence of any ATC speed control and any formal speed instruction printed on the arrival chart, I fly the speed I feel appropriate on the day. This may or may not fit in with other traffic so you guys need to tell us. (To digress, all too often high performance turboprops are shoved to the back of the queue and given a restrictive speed over 20nm out, when they are capable of maintaining 250kts until 10-12nm. Are all ATCOs aware just how early a 737 / A319 etc. needs to reduce to 210kts and below in comparison, not least the additional vortex gap they leave behind?)

My point is that, when I am so often given a speed of 210kts on arrival at the zone and receive no speed instruction thereafter, we cannot possibly maintain this until 4 DME. I see your point clearly but the fact remains many of you guys issue a speed when we are far out to suit your flow, and never get around to reducing us for the approach. It's around 8 DME we will reduce to circa 180kts if we haven't heard anything further from you. I certainly don't condone the ignorance by pilots of speed instructions when they go something along the lines of 250 / 210 / 180 / 160 to 4 DME. That's plain cheating and I share your annoyance.

To give you my take on your last question, although I have never seen official guidance, in practice if a slower speed is issued by ATC then I would configure the aircraft to start reducing immediately, with a view to being locked on the speed within 30secs, although this may take up to a minute on a medium jet.

[elcrusoe]

"As soon as you are cleared for the intrument app. it cancels any previous restriction unless otherwise specified"

You can find this quote in the FAAO 7110.65, i'm not sure if this rule is applied per the icao regulations since well i can't find a suitable copy to read without paying for it.

But overall this is how it works here in the US. At a busy terminal, We often will use the downwind to reduce guys to 4000 and 210kts. Once they hit base we will take them to 180kts. Following the app clearance the ATCO will instruct the aircraft to maintain a certain speed in between 160 to 180kts until the FAF, OM, or a point at about a 5 mile final. After the 5 mile point the pilot is in commend of the required speed for touchdown. To do so we take in to consideration the compression effect. A 747,767 or even 757 will run down to about 110 to 130kts short final therefore to maintain a wake turbulence separation you must plan accordingly with the next aircraft. Give a little more room. An Airbus will slow more then a boeing most of the time in my experience.

But a good hint, or this is how i think the faster i get my final so if i can keep the final at about 180kts.......well the closer my final will be to the airport.....i don't want a final passed 20nm cuz that means more work for me. And well the faster the final the quicker i get the A/C to the tower so less R/T issues.

But well i hope this helps out the questions a little.

Take care people.

[2.5 miles]

UK AIP London Heathrow Aerodrome section EGLL 1-18

"Speed Control: Pilots should typically expect the following speed restrictions to be enforced; 220kts from the holding facility during the initial approach phase; 180kts on base leg/closing headings to final approach; between 180kts and 160kts when established on final approach and thereafter 160kts to 4 DME. These speeds are applied for ATC separation purposes and are mandatory. In the event of a new (non speed related) ATC instruction being issued (eg an instruction to descend on ILS) pilots shall continue to maintain the previously allocated speed. All speeds should be flown as accurately as possible. Aircraft unable to conform to these speeds must inform ATC and state what speeds can be used. In the interests of accurate spacing, pilots are requested to comply with speed adjustments as promptly as is feasible within their own operational constraints. Pilots should advise ATC if circumstances necessitate a change of speed for aircraft performance reasons."

In high traffic density environment, where a high landing rate is necessary, such constraints are essential. This is particularly essential when we are applying 2.5mile separation, there is little or no room for error, hence the above. The caveat being, if you can't comply, let us know and we will compensate.

Hope that helps:)

[av8boy]

Our JO 7110.65S says it this way in Chapter 5, "Radar," Section 7, "Speed Adjustment," Paragraph 5-7-1, "Application:"

[Snip]

b. Do not assign speed adjustment to aircraft:

1. At or above FL 390 without pilot consent.


2. Executing a published high altitude instrument approach procedure.3. In a holding pattern.4. Inside the final approach fix on final or a point 5 miles from the runway, whichever is closer to the runway.c. At the time approach clearance is issued, previously issued speed adjustments shall be restated if required.



d. Approach clearances cancel any previously assigned speed adjustment. Pilots are expected to make their own speed adjustments to complete the approach unless the adjustments are restated.

[Snip]

Of course, I prefer "two-ten to the marker, faster if you like." :)

Dave

[Kiltie]

Thanks 2.5 miles, but that's a local arrangement particular to Heathrow, and is similar to that we see printed at other airports of significant traffic levels. However, many other places have no such printed speed requirements and it's at these places that I tend to experience the problem of an initial ATC speed given but then never reduced thereafter, leaving the onus on the pilot to reduce at a sensible range....

It bemuses me why anyone would want to cheat at ATC dictated speeds; an extra 10 or 20 knots won't make a damned bit of difference to an arrival time. Perhaps it is a fixation by the pilot of trying to achieve the perfect pre-programmed VNAV CDA without budging the thrust levers out of idle. Anyway with the advent of Mode S can't you interrogate what IAS the pilot has, "spot the liars" and bring them to task?!