View Full Version : LGW Approach 20/3
A gentle plea for Director? We had a successful thread here a while back about ideal speeds for a/c on finals, and I remember 170 kts being a ??concensus? target. Yesterday (difficult winds for ATC, I know) we (B737) were asked for 160kts at 18.5 DME (over Tunbridge Wells) which requires gear down. I asked for 170 to be told (abruptly!) 'too late', at which point the controller handed over to another( :D ). This gave us a groundspeed of between 98 and 101 kts from 18 to 4, both burning a stack of fuel and making mucho DB over the 7 minutes.
Obviously there were problems with spacing with those winds, but we DO genuinely try to save fuel (both for the environment and my shares:p ) and try for CDAs, both of which went out of the window. Planning for diversion fuel was also trashed by the requirement for gear that far out.
If you can bear in mind the dramatic increase in fuel/noise that 160kts (737) brings, we would be grateful.
Warped Factor
21st Mar 2004, 09:40
The 160/170 speed issue for 737s is a bit of a Catch 22 for ATC as there seems not to be much consistency.
On the occasions that I do Gatwick, when spacing is not an issue, I often say "descend ILS, speed now either 160 to four or 170 to five".
Nine times out of ten the reply comes back, "roger, we'll do 160 to four".
Then, when spacing is an issue and I've got a 737 nicely three miles behind something else and I say "speed now 160 to four", I can almost guarantee the reply will come back, "can we do 170?" That is too late.
All I'd like to say is if a particular speed on final is needed for whatever reason, please state this asap, don't leave it till base leg or final. We want to provide the best service possible, but need the request in enough time to be able to act on it.
WF.
Thanks, WF, we do normally give warning if we think we need to - but getting the change so far out caught me unawares:confused:
There SHOULD be consistency on the speed for 73's (2/3/4/500) as we thrashed this out on this forum a couple of years ago, and 160 requires gear down, 170 does not.
Found this (http://www.pprune.org/forums/showthread.php?s=&threadid=15896&highlight=approach) thread and my original (http://www.pprune.org/forums/showthread.php?s=&threadid=15896&highlight=approach)
Worth opening up the discussion again guys?
Scott Voigt
22nd Mar 2004, 03:11
Shoot, consistency by flight crews flying would be a god send... We can't get the same company flying the same aircraft the same way much less the same aircraft from different companies.
It is nice that the crews are trying to save the environment and the company some money. However, if we can't keep safe separation then you get a go around and how much money have you saved the company? Are we perfect at what we do? Nope, but we do our best with what is given to us. If there is no traffic to be concerned about then we try to let you do what you want with YOUR economic considerations. Otherwise though our first and foremost concern is that of separation and second is that of capacity to the airport (what REALLY matters to the air carriers bottom line.) and everything else is secondary...
regards
Scott
ea306
22nd Mar 2004, 04:35
170kts = gear up..... whereas 160kts = gear down.
Why not use Flap 10 speed 160 gear up and save some fuel and noise?
Block speeds allow for this. Just remember to call for gear down and have 3 green lights before selecting Flap 15 to avoid the warning horn. However I am sure you are aware of this.
Is this restriction simply due to company SOP? And if so, does the SOP allow for good discretion to alter as needed to get the job done?
Just a thought.
sv - I did say it was not a 'pop' at ATC, but trying to inform! My only query to your post is was separation degraded by 160 to 4 from 18.5 miles as opposed to 170 to 6 etc?
Shoot, consistency by flight crews flying would be a god send - that is why these forums are so useful!! - hence
Worth opening up the discussion again guys?
ea - Boeing changed the manoeuvre speeds a while back to make 170 the minimum for Flap 10 (737 3/4/500) at normal weights following suspected rudder hard-overs where insufficient control was available at 160kts. 160 requires gear to avoid the warning horn at F15 you mention.
The Greaser
22nd Mar 2004, 08:30
To add another spanner in the works, the NG 737's will comfortably fly 160 with flap 5, no gear required.
Nice spanner, Greaser! In a long-since discussion on Pprune (before 'NG's) we settled on 230 clean, and 170 intermediate as a compromise for all a/c big and small. Does that fit the NG?
Del Prado
22nd Mar 2004, 12:03
BOAC said -
-------------------------------------------------------------------------------------------------------------------------------------------------------------- My only query to your post is was separation degraded by 160 to 4 from 18.5 miles as opposed to 170 to 6 etc?
---------------------------------------------------------------------------------------------------------------------
Assuming a ground speed of 100kts I reckon the catch up would be 42 seconds or just over 1 mile.
If you were 3 miles behind the preceeding at 18 miles, by 6 dme the separation would be less than 2. (and the controller would be suspended).
That's not to say you wouldn't get landing clearance but SEPARATION would have been lost.
In my experience, 170 kts to 4 is only suitable to a small number of aircraft. Not every 737 wants 170 to 4.
747, 757, 767 and all the airbuses seem to manage 160 to 4 so why change the standard to suit a small minority ?
That's not to say I won't accomodate 170 to 4 on an individual basis if I can but you cannot wait till minimum spacing is established then say 'can we do 170 ?', it just won't work.
To further illustrate my point, one of your collegues in a -500 last night waited till on the tower frequency to say they had a particularly low approach speed and were slowing early. The company 737 three miles behind very quickly became 2 miles behind and only a rapid speed reduction avoided a go around.
It beggars belief that a small minority of pilots don't realise the impact a change in speed has on spacing and separation.
BOAC, if you want 170 to 4 ask downwind or even on base leg and if you do ask later than base, don't be surprised or offended when we say no.
Thanks DP - the original post was about an unusual and very early speed reduction. You are correct in the 1nm loss of separation, assuming that the preceding was also 'dragging it in' from Kent! We were 6 behind a medium.
NB The variation I was asking about was 170 to SIX, not FOUR - and I speak NOT for my 'fellow Nigels'!!:eek:
ea306
23rd Mar 2004, 06:25
BOAC
I am of the understanding that the revised block speeds were a temporary measure until the RPR mod was accomplished for the rudder.
The A/C I am operating at present have had this mod done and the revised block speeds are no longer in effect... unless there is something I have missed and should be aware of.
Comments?
Still effective in BA. Heaven knows! I'll ask some questions. PM on its way.
Right Way Up
23rd Mar 2004, 08:05
The block speed for for the -300/400/500 with Flap 10 is 170 kts whether or not RPR is fitted/serviceable. (courtesy of Boeing bulletin) .
EA306 I am guessing you fly -100/200 which with RPR working the block speed for Flap10 is 160 kts.
P.s. Question for ATC@Lgw. When we give our life story to you on first contact, the fact we confirm our aircraft type, does that mean you will give us vectors and descent based on our known performance. i.e. the difference between an NG and -300 descent profile is chalk and cheese, especailly at clean speed.
PPs IMHO the controllers at LGW are probably some of the best in the business. Amazing what they do with a single runway in such an overcrowded TMA.
Del Prado
23rd Mar 2004, 12:16
Right Way Up,
the simple answer to your question is no.
we check the aircraft types to verify they are the same as flight plan.
a repetitive flight plan could show a 737 but the operator could have put a 757 or 767 on the route with no flight plan amendment.
there are obvious issues with vortex wake.
an accurate aircraft type also helps the tower with conditional line up clearances.
ATC doesn't need the type of 737 just a confirmation that it is a 737.
saying you're a "-400 series" on first call doesn't help, i want to know if it's a 737, 747 or dash 8. :D
*******IMHO the controllers at LGW are probably some of the best in the business. Amazing what they do with a single runway in such an overcrowded TMA*******
It can't be done without the co-operation and professionalism of the crews that regularly fly in and out of Gatwick.
Well, to avoid boring discussions of airline sops, is there any chance we could revert to the 'offer' which we negotiated a while back of 160 to 4 or 170 to xx (6, maybe?). This would benefit both noise and fuel.
Del Prado
23rd Mar 2004, 16:15
At gatwick there are dozens of operators flying every variant of 737 and each operator seems to fly them differently.
That is evident both from this and previous threads and indeed you say you speak not for your fellow 'nigels'.
Rather than change the standard for all 737's when it seems doubtful this would suit all crews, can I ask you to make a polite request as early as possible on 126.82 ?
an early request can usually be accomodated.
after a while, we may learn who to expect will request 170kts and you will learn when a request is likely to be denied.
A blanket 170 to 6 for all 737's is going to have an adverse effect on the runway movement rate and increase the number of go-arounds.
Will do that DP. It was the 18.5 mile crawl that threw me the other evening :D
you say you speak not for your fellow 'nigels'.
That was regarding the guy who threw the early slow-up! I think all 'N's' would be happy with 170.
A blanket 170 to 6 for all 737's is going to have an adverse effect on the runway movement rate and increase the number of go-arounds.
Not quite sure what the difference is here, but I'll take your word for it! We had worked out (via PPrune) in the past that 170 was ok for all jets including the heavies.
PS It was 170 to xx for you to fill in the xx!
ea306
23rd Mar 2004, 20:14
BOAC
Yes I am flying the old 200..... so that explains the 160kt F10 gear up config.
Going on the NG next year.(thank goodness)
A310 quite happy S/F 15/15 gear up 170kts.... previous type... previous company... previous life.
Cheers
Right Way Up
23rd Mar 2004, 21:09
It seems a shame with the amount of 737-3/4/500s @ Lgw that we could not sort out a system to overcome this problem. LGW is such a noise sensitive airfield especially with recent events. Being asked to do 160 from 10 miles means a lot of unnecessary noise. Certainly not ATC's fault, but unavoidable with the 73's ops requirements.
LateLandingClearance
24th Mar 2004, 16:35
@ Del Prado
ATC doesn't need the type of 737 just a confirmation that it is a 737.
Maybe not for approach, but in the tower it can have quite significant effects. Such things as restrictions on the ground as to what size aircraft can go where and park where. Therefore, when you get your type check from the inbounds on their first contact, it's not just for your benefit - it has knock ons all the way until it parks on a stand. So if it the declared type doesn't match what's on the strips - please make sure you're passing that info on the us in the tower.
Scott Voigt
25th Mar 2004, 03:29
Actually, enroute needs to know too. That is how we can tell just what an aircraft can do. There is a big difference between the 732, 73Q, 733, 737 etc...
regards
Scott
Del Prado
25th Mar 2004, 11:30
LLC,
In that case I stand corrected.
Excluding the Northern Runway, where are the taxiway restrictions at Gatwick for different types of 737 ?
I do check the different type of 747, but to the best of my knowledge, we've never been asked to check other variants.
Indeed, I've discussed this a couple of times when the type change has been A320 to A321 or vice versa and the tower controller said it didn't really matter.
BOAC,
170 to 6 (for example) would work for all jets.
However, inside 6 dme an emirates 777 might slow to 160 and the 737-500 ahead might slow to 120. Thats 50% faster over nearly six miles. We'd have to increase the spacing between arrivals and the movement rate would suffer.
The bottom line is the efficiency of the runway and while it might be 'nice' to let you all fly the speeds you want, the airlines (not least BA) are not prepared to pay the cost of losing 4 or 5 movements per hour.
If, on the other hand, we have a stream of 737s and they all request 170 kts to 5 then that's easy to provide, good for the enviromentals and most importantly the landing rate does not suffer.
It just depends on the circumstances, that's why I think 160 should be the norm, but we should provide 170 when able and when requested.
I'd be very interested to know how many of the 737 flights into gatwick have to drop the gear to achieve 160 and whether that is dependant on variant, weight or operator. It's been discussed many times but we don't have a definitive answer.
LateLandingClearance
25th Mar 2004, 18:11
Various restictions around the airfield. Such things as what can park on the remote holding stands, whether X can pass behind Y when one is holding at a holding point.
Similar restirctions apply to airbuses (320/321).
Right Way Up
25th Mar 2004, 18:33
Del Prado. The speeds the aircraft slow down to should not be a problem. Slowing down at 5/6 miles should let the aircraft pass roughly 160/150 at 4 dme slowing to their final app speed. Although sometimes I wish it was the case a 737 cannot slow from 170 to 120kts instantaneously!
p.s. without exception every -3/4/500 operator will drop the gear if required to keep 160 kts. Unless they are deaf.:D
DP - ALL 737 3/4/500 will need the gear for 160kts. This restriction can (apparently) be lifted when a Boeing rudder mod is incorporated, but BA (and I suspect most) operators will wait until their WHOLE fleet is done before changing the speed restrictions piecemeal.
This current 'issue' was triggered by a specific very early speed reduction request. Gear down at 18.5 will probably double the overall fuel consumption for an approach. We (BA) are ??normally?? putting gear down at between 5 and 7 miles on an unrestricted approach (standing by for rhubarbs!), so if the speed requirement is not too far away from that, 160 to 4 is a doddle! It is trying to satisfy ALL the inputs that is difficult - yours, ours, 'airfield neighbours' and the accountants!
FYI, at normal weights, flap 5 has a lower limit of 180kts, flap 10 170, and flap 15 150, but requires gear down. These figures are for the 737 3/4/5 and I detect that the NG 737 has different speeds. We have heard nothing form the AB319/20/21 brigade yet.
It is very unusual to have an approach speed of 120kts in a 737. 140 is more normal.
blondie118
30th Mar 2004, 01:18
I work Essex radar and when I can I do try to offer the B733's 170kts to 5 DME OR 160kts to 4DME and let them decide.
Granted at the end of the day I don't always offer it to everybody as there's not always the time but I'm happy if they ask.
I suppose at the end of the day it's down to the controller but my theory is that it can't hurt to ask. I accommodate requests when I can, I can't do anymore than that. That's just me though, I can't speak for other controllers or sectors.
:)
The 'asking' seems to be working at LGW at the moment. It does generate extra R/T, and the difficulty for me is in knowing whether it will be relevant i.e. whether it would be applied at around 10-11 miles, when it really doesn't matter that much (160 - gear or 170 - no gear), or whether it will be a 'surprise' at 18.5 miles finals in a 60kt headwind when it does. Finding the right form of words is a trial too!
Warped Factor
30th Mar 2004, 08:14
I offered every single 737 I spoke to at Gatwick yesterday the choice of 160 to four or 170 to five, and that was quite a few :)
The outcome was that two or three came back with "we'll do 170" and all the others said "we'll do 160".
Distances from touchdown when offered were anywhere from around 16nm out to around 8nm.
I offer no opinion on this other than what I originally said, that there does seem to be a lack of consistency. But if you specifically want one or t'other plase ask, preferably before turning base.
WF.
WF - I appreciate your interest in this:
that there does seem to be a lack of consistency.
Distances from touchdown when offered were anywhere from around 16nm out to around 8nm
I cannot be sure, but that may well contribute to the perceived 'inconsistency'? We have NO SOP, except that we try to minimise noise and conserve fuel, and this really is the point of my post. It doesn't matter 'a fig' from the handling point of view. The only 'fixed' target is to be in the approach config. with speed around target approach speed at 1000'AAL, i.e. just over 3 miles. This may have been the earlier problem you referred to with a light a/c = low approach speed - accepted some notice would have 'professional'!
As I said above, 160 to 4 requested at 8 miles is a total non-event. Requested at 18.5 with a G/S of 98kts is not.
Oh for some more famil rides!! As an aside, what is happening when you guys and girls ask for them? I am not seeing any arrive at the f/deck door :confused:
Warped Factor
31st Mar 2004, 19:00
BOAC,
Oh for some more famil rides!! As an aside, what is happening when you guys and girls ask for them? I am not seeing any arrive at the f/deck door
The NATS fam flights scheme stopped following 9/11.
I think they're back on the agenda now but the days of us just asking when on board if we can sit up front are gone I suspect, any we do now have to be arranged through official channels weeks in advance.
I recall seeing something about a very limited number of BAW trips available for TC folks recently, but can't remember any details.
WF.
Sorry, WF, I misled you - I was not talking about 'ad-hoc' f/deck visits, but officially arranged ones. I understood from a thread here post 9/11 that they were 'back-in-business' and I was wondering what the response to those requests was? There is certainly no problem in our carriage as long as the 'official' clearance has been obtained- and I'm sure I speak for all when I say we'd be delighted to see you all - well.......not ALL (at once):D