BOAC

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( ). 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 ) 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

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.

BOAC

Thanks, WF, we do normally give warning if we think we need to - but getting the change so far out caught me unawares

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 thread and my original

Worth opening up the discussion again guys?

Scott Voigt

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

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.

BOAC

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?

- that is why these forums are so useful!! - hence

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

To add another spanner in the works, the NG 737's will comfortably fly 160 with flap 5, no gear required.

BOAC

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

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.

BOAC

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'!!

ea306

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?

BOAC

Still effective in BA. Heaven knows! I'll ask some questions. PM on its way.

Right Way Up

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

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.

*******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.

BOAC

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

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.

BOAC

Will do that DP. It was the 18.5 mile crawl that threw me the other evening

That was regarding the guy who threw the early slow-up! I think all 'N's' would be happy with 170.

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

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

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

@ Del Prado

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.