Probably 95% accurate but the trombone allows the order to be ever so slightly fine tuned to allow for some wake turbulence efficiencies as well as allowing having enough aircraft in the right spot to keep pressure on the final spacing. For example, I witnessed a super 'shortcut' to follow another super when there was a 737 in between intitially with the 73 extended downwind. The crux of your point is valid though. The same overall cumulative delay for the entire sequence will be very very close to exactly the same (minus the above as described, so maybe a movement an hour).

Lol, true, the GAF factor seems to be decreasing a lot lately... inducing many :ugh: moments for quite a few of us...

See now that would be an ideal solution except you forget it probably doesn't make much difference since many of our pax seem to see the s/b sign coming on as a flashing "Go Pee Now" sign and it takes longer to get them sitting down again (unless of course you are me and just keep knocking on the door til they come out of the lav shame faced, seems to work a trick to tell them we can't land til they do and they are making everyone else late :E)

I have nothing but respect for our controller colleagues, however, I am bound to wonder at some of the techniques used early this morning.
Reduce to 230 kts in the descent, headings in the region of 60 degrees off track, one way and then t'other.
Then increase to 250 for about 2 minutes, then back to to 230!
How can 230kts at 10,000ft with 125 track miles to run on the STAR be described in anyway as efficient?! Not to mention the light chop frequently encountered at that level.

Is it the mix of heavy and medium, and the high density periods?
Many years at LGW, with its single runway, elicit nothing more than massive respect and admiration!

The heavy/ medium mix isn't really a problem - only 1 more mile.

However, when you add the whales into the picture, including the fact that they are so slow in the last 5 miles that we have to give an EXTRA 2 miles spacing in the sure and certain knowledge that it WILL erode, it quickly has an effect!

The arrival speed that was once 250 knots is now 230. Once 1 aircraft gets to the fix, everyone else gets the speed when there is any form of a sequence. Expect it from LABTA and ENASA from 7pm local onwards till 2am and if you don't get it that is a bonus.

Guy D,

The whale has a Vapp in the 140kt range, which is pretty close to everything else except a 773 or an MD11.
Taking that the last last 5nm takes 2.5ish min you would need to have a 160kt Vapp aircraft following (ie 773 or MD11) to lose the 1nm in 3min or a 190kt Vapp aircraft to lose the 2 nm in 3min, so I can't figure how this final 5nm applies to the whale only, as it would be for all 140kt Vapp aircraft right? Could you explain it to me please?

The Don

OK, 230 instead of 250 at ENASA, and FL 280 I think. Fair enough.
But what about the 125 miles at 10k?

Don,

Not sure whether it is linked to the huge area of drag surfaces available or other factors come into play but the 380 loses speed much more quickly than just about everything else that flies in here (even the 330s), after the speed limitation expires. Our radar only shows groundspeed at the mo and it usually shows them grounding at 135 kts or so - often already at 5 miles out, where almost everything else is still showing 160-170. That's half a mile a minute of difference, which would already give at least 1 mile of reduction on final.
Experience has shown that spacing continues to reduce and, short of asking the following traffic to fly 140kts 8-9 miles out (which I personally hate to do - others don't) or go-around, the only other way of ensuring adequate spacing when the 380 touches down (as we are required to do - there is NO leeway) is to provide it when the second a/c turns inbound. I personally always use 2 miles extra - depending on the winds, this always reduces by more than a mile and often by the full two.

Guy,

What am I missing? If the lead traffic, worst case, instantly slows to 140 @ 5 miles, as it touches down the following fraffic is still @ 6 miles doing 160 if the lead is a 380. As you said above, the separation will reduce by approx 1 mile. Surely this is built into your inital spacing.
Alternatively, when you get your IAS readout, let's see who slows early!

Yo,

As I said - not sure where the miles go or whose "fault" it is - just relaying my observations and experience. Given that it happens on virtually each and every occasion, there IS a root cause - the above is my way of dealing with it such that sep is maintained and I don't need you to drag absolutely everything out at 10 miles.

Without wishing to upset anyone, one of the contributing factors is that the number of people reporting 160knts is often unrelated to the number actually flying the speed they report. If you don't fly the assigned speeds accurately how can we be expected to achieve any standardisation in final approach spacing?
Differences in ground speed of sixty knots and more is not that unusual between an a/c at five miles and one at eleven miles and as a Tower controller they are not many options when faced with anything over half mile a minute catch ups.

Guy and Tower thanks for that. The 380 seems to hit Vapp around at around 1000' if flap full is taken at 1500' and speed is reduced from 160kts at 5nm. Pretty much the same as the 330/340. I guess as tower says it all depends on what speed is actually flown and when it is actually reduced.

Was given descend to 10000' at 2000fpm and 230kts at 120 miles the other night. Only cost 1500kgs of extra fuel to what the predicted for the approach. It would be nice if DXB was given a bit more upper airspace if it would help with the extremely early descents.

the Don

Question: when the man on the radio says 180 kts to ten, 160 to 5, what do they really mean? What are they expecting? Is it the same as at LHR where they expect 180 reducing slowly to be 160 at 4?

Exactly that. 180kts to 10 miles. No more, no less. Then back to 160 kts ASAP. And hold that to 4 miles. Not 5 or 6 miles, unless instructed.

If you need 165 kts or can only give 160kts to 5 miles, speak up. We'll adjust the spacing behind you.
Being within 5-10 kts of assigned speed on arrival or downwind is acceptable. Not on final where we get put over the GCAA's knee and spanked when wake is infringed because someone doesn't do their assigned speeds. Couple too many of those and we might have to start the job application process somewhere else in the world.

Crux of the matter is - Speak up if you can't comply with speeds, or ask if you can fly a certain preferred speed. Throw us a bone!!

My point is CEP, that large heavy aircraft do not lose 20 kts immediately. What rate are you planning for the speed reduction?

Guy, you're rattling at the pride of the dugong jockeys, be careful!:\

But putting sarcasm aside, why would anyone doubt your observation, with our tunnel and one sided vision anyway?

Fact is the trouble increased exponentially once some dugongs started sharing the airspace. We even experience some taking these things ahead of us, apparently to group arrivals. That might make sense from a global/atc point of view, but not to other aircraft who have been given EATs and 2% STATCON, just to have the times swapped and extended without notice. Don't even dare ask why on the radio .... just commit or divert.

Too many different speed characteristics don't mix well, I get that. I also truly think that time will smooth things out. But there's no doubt that today the 380 slows things down. We all have to adapt, that means comply with the speed constraints, sure, and we do. But that should go both ways! Even the big things could adapt to usual speeds, especially because it seems to slow like a brick, meaning it could keep a civilised speed for a slightly longer period. Just a suggestion ..... :ok:

3 wire, FMS speed dial up
 

If a speed reduction is requested, dial it into speed command, and let system adjust, theis should take 3-5 seconds, i suspect.


previous posts suggest 380 should decrease like a brick shute house.

glf

That would seem to indicate that the big one is slowing earlier than the rest.
Would anyone flying it care to comment? 160 to 4 can look pretty fast some times.
This thread is a timely reminder to those that sometimes forget that they are not the only ones in the sky!
Ps. It still doesn't explain the 10k 125 nm out!!:cool:

Three Wire - depends on a/c type, but generally I expect 2-3 miles before that 20kts is bled off.

TowerRanger - Hopefully we'll get a link to RAK's new mode S radar......then we'll be able to see what's actually happening with those speeds.....

I must be a simpleton, I was under the impression that when given 160/4 that meant we reduce to this as we can, i.e. as succinctly as possible.
What still truly baffles me is the amount of guys who bitch and moan about ATC speed requirements....and do their own thing...rather than a simple "unable...we require 170/5 etc etc"
I see very senior and junior 777 guys in equal measure struggle with this concept..the concept that whilst we all work together, ATC exist to provide aircraft a service within the regulatory and airspace framework.
Guys if you can't make the speed, just fecking tell them! "UNABLE"