Speed control

[gjp]

Please can you explain how speed control is applied..

1. If given a speed to fly (When flying a RNAV app with speed constraints) and you change to another controller do you maintain your previous given speed and exceeed your RNAV arrival speed or do you adv the contrioller of your amended speed

2. Do you fly the previous speed and reduce to normal RNAV arrival constraints when changing to another controller.

3. I have found that for example, that at LHR you fly the speed you have been given even when changing to another controller but this is not the case for example, in CDG where you have to
tell them that you are maintaining a speed and that you would like to reduce your speed.

I am after a professional opinion as I have been flying into Airport around the nworl and find that there is no specific rule and it becomes very confusing as we - pilots - are trying to fly CDA's but find it very difficult in modern aircraft as they are so efficient that slowing down on the appr is rather difficult if you are not sure of what ATC speed control is required.

Please reply with a professional answer as it is becoming an increasingly problem with non standard operations and requirements from ATC, we, the pilots, have amazing technology at our disposal but find that the different requirements from the ATC's around the world make it very difficult.

Hoping for a good respone,

GJP

[Scott Voigt]

Hi GJP'

It should be the same in the UK, but in the US, if you are assigned a speed to fly, then that is a clearance and you should fly that speed until other wise told. If you have a question, by all means ask. One of the clearances I would give quite often was maintain 300 KIAS until Bonham, then comply with the speeds on the STAR.

There is indeed a LOT of nice new functions available in some cockpits. The problem being though that to program a lot of these takes time and then also takes away the flexibility that we as controllers have in moving traffic. Until they make the newer avionics as easy to use as grabbing a handfull of throttle to adjust speed, or twisting the OBS so as to intercept a course, it is going to make both of our jobs tougher.

Yes, we could comply with the problems doled out by your automation and let you program your route and then just fly it unadorned with anything else. But then you would see the flow rates in and out of airports go down quite a bit when the flexibility is taken away.

regards

Scott H. Voigt
NATCA Southwest Region
Safety and Technology Chairman

[radar707]

In the UK, if you are given a speed then that is the speed you shoud fly at, on handover to the next controller, you pass all the relevant details, i.e callsign, routeing, level/cleared level etc, but also pass your speed, e.g XXX123 passing 80 for 70 speed 250 at the moment but we'd like to reduce.

As an approach controller there are many times that I would prefer it if you could fly faster than the speed assigned by the area controller (for sequencing purposes), then i'll tell you no ATC speed restriction and ask if you can increase, I appreciate there are limitations relevant to a/c or company and we do get used to these, e.g Easyjet 250 below 100 unless specifically asked by ATC to fly faster.

As an aside my thanks to the ATP drivers at Glasgow who used to (unfortunately company put a stop to it) give us anything up to 230 to 4d.

If you want to fly slower then ask if you can reduce, if you HAVE to reduce then tell us, it may mean you get pushed back a place in the sequence but it helps us with the big picture and reduces holding and delays further back in the line.

[gjp]

Thanks for the response - good info.

What happens, before descent generally, is that we set up our FMS for the Rnav. The constraints are pre programed including speed limits. You then follow your profile for Star and , if in fully managed mode, the aircraft will do the rest. Should you require any speed or altitude changes we can make them either by changing the constraints on the Fms (Which we regard as long term changes) or can select them as required (short term changes) - this is very easy to do - not a problem at all.

Where the problem is, is trying to establish what the controller wants ie...

Assume my Fms has the aircraft flying descent at m0.82/ias 320 with a constraint of 250 ias at 60nm from the airport and 220 ias at Iaf which typically is about 20 nm from airport...

Area gives me 280 ias during the descent- so I then select this speed of 280 (I am now in what is called selected speed). I then am tranferred to Approach control. I would normally continue at the 280 ias unless adv otherwise (Normally I would not give my speed as I expect that Appr and Area control have agreed on the speed for flow control) Just before the Iaf (which requires 220 ias at Iaf as per the pre programed speed constraint) I am still doing 280 ias. This is not a problem from a performance point of view but I am about to be handed over to the Final controller doing 280 ias. The final controller then turns me onto a Hdg then asks for 210 Ias - I then select 210 Ias. Aircraft slows as required and if I have a problem with my profile I then request a speed adjustment.

This is how I expect it happens - I do find that in practice there are different understandings on this subject - both from the Pilots and Atc;s point of view, (Prob more from Pilots point of view)

By the way, I am operating A340 and feel that the systems are very good and make our jobs much easier. Perhaps what is required is the good old "visit to the ATC centre" like we used to do in the good old times. Problem is that we travel to so many different countries and airfiels it takes some time to become familier with local procedures.

Thanks for the above professional response - much appreciated.

[Canoehead]

If I can add to the above; I would say that once you've done your profile descent and you come through 10,000 ft, you slow to 250 (at least in Canada), then, on the downwind abeam the field, slow to 210, on base 210 or less if requested, then at 10 miles final work the speed back to cross the O/M at around 170, (although on final you'll probably be assigned a speed for traffic). To me, the greatest irriatation is someone who decides (on their own) to slow to 160 when still on base or a 15 mile final. Screws everything up. If you really need to do this (turbulence, unfamiliar crews, new aircraft) please advise ahead of time, and I'll treat you like a light twin. And a small personal gripe: I do NOT need you to come on and tell me "XXX we're now fully established on the localizer......") I KNOW! I vectored you there. I can see you! Thanks and best wishes.

[StillDark&Hungry]

gjp

As has been said "If in doubt, ask"

Personally, as an Area bod, I'd be the one to give you the 280 restriction.
Hopefully, the way it's given should help you understand why the restriction is applied though; for example if you look like being no. 1 from our direction with little sign of terminal delays you might be given "300 or more" which I would hope gives the impression of being 1st! Or, "fly at 290 knots" means "meat in the sandwich" Or, "280 or less" means nothing behind you to catch you up!

Alternatively, we could be looking at the stacks seeing the traffic building up and simply don't want you piling in hell for leather!