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!

[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]

Delhi

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]

yes but...

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!

[loubylou]

clr4takeoff

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.