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-   -   Flying slowly? PLEASE tell us!!! (https://www.pprune.org/tech-log/79381-flying-slowly-please-tell-us.html)

eyeinthesky 28th Jan 2003 10:03

It's very difficult o give trite answers to large subjects, but the common theme is COMMUNICATION. You tell us what you want, and we'll do the same, and we'll meet somewhere in the middle.

To answer a few specific points raised so far:

1) If you are told to maintain a specific speed, e.g. 300 kts, then you maintain that and report it to the next controller. If you are told "Not more than 300 kts etc" then you are expected to comply with any published speed restriction points or levels (e.g. 250kts at CLN on th ABBOT arrival or 250kts below FL100) unless the next controller cancels those. Seems pretty simple.

2) As has been vociferously but impolitely put by Eastern Wiseguy, we have to sort out the traffic as best we can in our own airspace, comply with standing agreements and coordination, and try and anticipate what the next guy will want. Sometimes, because of the narrowness of airspace and lack of levels, we have to use speed control to get you all through the gap, only for that speed control to be unnecessary thereafter. An example of this is again the ABBOT arrival for SS/GW. We have one place, LOGAN, and one level, FL180, through which we can point you at the next sector. If 3 of you arrive together, we have to use vectors and speed control to achieve 5 miles (minimum) in trail at the same level. That might mean the front one is asked to do 300 or more, the second 290 and the third 290 or less. Having achieved that trail, it may well be that the approach controller decides to reduce you to 220kts for a straight in or to reduce holding times. If we had not got you in trail he would not be able to do that, and you would have to go into the sector high and hold at Abbot to lose height. One we have got you all sorted at the same level and in trail, it is a RELATIVELY simple job to vary that speed, and you should not find it strange.

3) The same is true of being put over on a heading, only to be sent direct by the next guy. This may be because we have needed you on a heading and have taken you away from your standard route. It is sometimes difficult to second guess where the next guy will send you (it might be just the next fix on route or it might be 5 further on), so it is easiest to transfer you on the heading and let him decide.

The nub of the problem is that we have a choice between doing everything standard (no shortcuts, no high speed descents, no change of level from that filed in your plan (EasyJet please note!!) etc), or we can try and work to help you. The first will mean that there is no need for us to communicate variations to the next controller, but you might find it a little restrictive. It is in most ATCOs nature, however, to be flexible, and we will vary what we do to suit the conditions and try to fit in with you. We do not have time to ring up and coordinate every single variation, so it is approved practice for us to get you to tell the next guy what we told you. Seems reasonable.
By the way, I have lost count of the number of times I have had traffic about to exit the sector which requests a change of level. To achieve this will mean a phone call to the next sector to get their agreement to the new level. This delays your change of level. Far easier to transmit the following:
"Make that request with XXX on YYY.YYY, and inform them that you are released for climb/descent by this sector".
9 time out of 10 this is read back by the aircraft, only for the phone to ring 2 mins later from the next sector asking if the traffic is released for climb/descent. Who's not communicating now?

Back to the original question:

Yes please do tell us if the great Boeing design means that you can't exceed 270kts because of a lack of drain holes or whatever, or if company arrival restrictions mean you are descending your 747 from the Far East at 250kts instead of 300 kts. Likewise, if you have an 0601 restriction at LL, tell us BEFORE we send you direct to LAM and you then have to hold for 20 mins. Stay on the route and lose time that way.

Finally: BRING BACK FAM FLIGHTS!!

Raw Data 28th Jan 2003 12:51

eyeinthesky

Yep, all fair enough, as you say- communication. If you tell us why you do stuff (as some do), we can understand the restriction better.

BTW I think that sometimes, the new sector doesn't believe me when I tell him/her that the previous sector has released me for climb/descent, judging by the length of time it takes to get the clearance (roughly the same time as a quick phone call to the previous sector...)

So now we can talk about trust as well as communication... ;)

eyeinthesky 28th Jan 2003 15:35

I am one of the few who passes on such info over the R/T, and I get stick for it. For example, I will pass traffic info if I think you might want something to look at or if I have had to put on what you might think is an onerous restriction due to traffic. If, after such a restriction, you see another aircraft which I have pointed out whizzing across your nose 1000ft above or below, I hope that will help in your appreciation of the bigger picture. But as I say, I am in the minority. Most take the view: "IFR separation, no need to pass traffic" and of course ultimately they are right. But it does little to expand our mutual understanding.

Another thing while we are talking about trust and communication:

Be a pilot, not a computer operator.

Two examples:

1) Traffic at FL380 for LL. "London, XXX request descent" So you amend your plan to fit that request in. Then they sit there for another 15nm before descending, screwing up the amended plan. I know that what is happening is that the autopilot prompts you to reset level in MCP or something 15 miles before TOD, and then it follows the VNAV profile. But a little piloting appreciation will show that if you ask for descent we expect you to descend now.

2) Heard on N866 the other day:
"Jersey, XXX request descent" (probably prompted by the same event as above).
"XXX, company traffic opposite direction 1000ft below, descent in 10 miles"
"Roger, we have him on TCAS".

Not transmitted, but I and others immediately think: "Well why the **** did you ask, then?".:rolleyes:

Right Way Up 28th Jan 2003 23:37

The main reason for slow speed descents is the lowering of the cost index in the FMC. As someone else pointed out the 737NG gives roughly 260 kts in the descent( Although we up it to 280). Previously when I flew the 747-400 it used to give us 250 kts, which we upped to 300kts.

AirNoServicesAustralia 29th Jan 2003 04:25

All this cost index stuff makes me laugh.

Do the bean counters realise that if a certain aircraft type is always slower than its counterparts on its arrival, and the controllers are forever pulling everybody else back to stay behind this type, it won't be long before that aircraft type is "saving" money flying round in circles watching all the real aeroplanes fly past while he waits for a slot.

If you can't play with the big boys, controllers quickly get impatient and throw you out of the sandpit, and you'll sit on the sidelines with all the sad Dash-8's and BA146's.

vegas_jonny 29th Jan 2003 15:29

Correct me if I'm wrong (sure someone will) but flight plan speeds relate to cruise speeds and are transmitted as TAS. There is no such thing as a flight plan speed for the descent. So what's a slow speed? When do you want us to tell you? Having flown three different boeing twins so far in my career, each one has a diffrent econ descent speed. Until there is a dictat that 300kts (for example) is a mandatory speed, then its up to the commanders choice on the day. Subject of course to ATC decreeing otherwise.

radar707 29th Jan 2003 16:34

From an approach controller perspective:

1. I'll apply a speed restriction IF and only IF I need you to fly at that speed for separation purposes.

2. I may lift a speed restriction imposed by a previous sector because I don't need you to fly at 220kts, you can fly at whatever speed you like (is most economical)

3. I need to SEPARATE you from other traffic, so when you do SLOW down, TELL me (my predict vectors only work when I have them switched on)

4. If I tell you to descend, then DESCEND, don't hang about, if I want you to take your time I'll say WHEN READY

5. If I ask you to keep high speed, let me know if you can't (My thanks to all ATP pilots out there who fly into EGPF who do 230kts to 4dme when asked)

6. Come and see how it works at our side, we can all learn from each others experiences)

7. Do any of you know the legal speed limit for class E airspace?

8. Bring back FAM FLIGHTS

Finally I AM the final arbiter about what happens in the airspace I CONTROL, the captain is the final arbiter regarding the SAFETY of his aircraft. I would certainly hope that if a pilot thought that an instruction I had given was unsafe then (s)he would question it.

We all have ine aim, that is to get the a/c and pax to destination as safely as possible.

We operate on thre principles:

Safe, Orderly and Expeditious

In that ORDER.

HugMonster 29th Jan 2003 20:21

Sorry, radar707, but you're not the final arbiter about what happens in your airspace.

If you issue an instruction that an aircraft cannot comply with or which the aircraft commander considers unsafe, you can order him until you're blue in the face and it won't make any difference.

You are also not in control if we suffer a comms failure or almost any emergency.

I know that it's not written in MATS, but a pilot's priorities are:-
  1. Aviate
  2. Navigate
  3. Communicate
so talking to you is rather low on the list of priorities. Furthermore, the manner in which we carry out a flight is
  1. Safely
  2. Legally
  3. Expeditiously
Perhaps it's time that your priorities and ours reflected the same requirements?

To put the point brutally, if I have a problem I'll be telling you what I want from you and what I intend to do. I will not be making a request. You don't get a choice.

Sorry - but that's how it is. You are there to provide us with a service. Aircraft can still (and frequently do) fly without the aid of controllers.

COntrollers would not have much to do without aircraft.

The rest of your points well made. Like you, I regret the current lack of ability to familiarise ourselves with operations on the other's side of the airwaves.

eyeinthesky 30th Jan 2003 11:35

vegas jonny:

As Area controllers, we get used to the general principle that, all things being equal, jets tend to descend at a mach no until the IAS becomes the governing principle, and then they will descend at around 300kts until other speed restrictions take effect. There are variations within that (RYR 737-800s which have not been de-iced seem to hurtle around at 320 kts+!) but that is what we assume. If you vary that by a lot, while you do not have to tell us, the assumptions we make concerning your position relative to other traffic might prove awry and the point of the first post was to highlight this to you.

From your side, I squirm with embarrassment when I hear some of my colleagues asking traffic at FL300+ its IAS and then restricting it to that relatively low figure (260kts-) all the way down, along with everybody else behind. It shows a singular lack of appreciation of aircraft performance.

Regrettably, however, that is the way things are going these days. To keep costs down we are only training to the minimum standard, and peripheral knowledge is seen as unnecessary. How many times do you see questions posted on PPrune asking: "What is the answer to this question from the ATPL question bank?"? Rather than "Who can help me understand this subject?".:rolleyes:

radar707 30th Jan 2003 15:10

Hugmonster, I appreciate the point you are making and agree that a pilot commanding an aircraft in an emergency will do what he wants to do, and I shall do everything in my power to assist him.

However, if pilots routinely ignored ignored instructions from controllers in controlled airspace because they thought it wasn't safe, then anarchy would reign supreme. Pilots don't always have the whole picture with regards to what is going on around them. TCAS separation is not a legal separation standard,

I know what is going on in the airspace I CONTROL.

Captain Stable 30th Jan 2003 17:03

I don't think anyone has suggested that it is acceptable for pilots to ignore instructions they consider unsafe.

The only acceptable response is "Unable to comply due..."

For the rest of it, my understanding has always been that ATC are there to facilitate the safe conclusion of the flight. They provide a service, but when the chips are down, whether flying in the London TMA or anywhere else, the FINAL arbiter of what goes on is the aircraft captain.

Captain Cautious 4th Feb 2003 11:35

An enlightening thread.
As has already been mentioned the root of this problem is communication, and at least we are doing that here!
The original post seemed to point a finger at a/c arriving into LTN and STN, and in particular the B737. Well that's my patch so I'm listening up! I here the gripes from ATC here, I'll take note and pass some of these comments on to my colleagues.
I think the point has already been made that there is no such thing as a standard speed in the descent above FL100. There is great variation between company SOPs, a/c types and cost indices flown. So the assumption that everyone is flying at 300kts is ill-founded. If you have a 747 at 250kts and a 737 at 320kts catching him, can you not tell from the vector on your screen? If you need them to alter speed either up or down, just ask. After all, you are in control of your bit of the sky! If he is unable to do so he should tell you.
Alternatively, we could report our speed to each new sector, but I think you'd agree that would be rather over-the-top!

Regarding the intermediate approach phase, there is an increasing amount of standardisation here. 210kts initial vectors, 180kt final vectors and 160kts to 4nm on the glide, or something similar. However, I believe a 747 is almost falling from the sky at 160kts, whilst my little 737 requires some swift deceleration to be stable by 1000' agl,(Company SOP), and can prove impossible. But again communication is the key.

ATC fam. flights would be great, but as KRISKROSS says, in our company nobody enters the flightdeck anymore except for the operating crew. I read another thread on Prunne recently that spoke of a DfT / CAA ruling banning non-crew from the flightdeck. Does anyone know where I can obtain a copy of this ruling?


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