How can Heathrow so many movements?

[Spitfire01234]

Hello,
I'm working on my diploma thesis dealing about the modelling of runway capacities. At the moment I'm trying to validate my simulation results with the declared capacities. Unfortunately regarding London-Heathrow, there is a rather big gap between my results and the "real life values".
When I'm right, Heathrow operates in segregated mode like ,for example, Airport Manchester as well. But how is Heathrow able to handle much more traffic (~85 in contrast to ~65 movements per hour)? Does Heathrow use speacial operations or reduced (radar/wake vortex) separations? Many thanks for your help!

[DaveReidUK]

One obvious difference, which you will no doubt have noticed, is that Heathrow's runways are 1400m apart, whereas there is less than 400m between those at Manchester.

[mad_jock]

if you look at the AIP they have some stuff on the special air qualities around LHR to do with wake turbulence

[Eric T Cartman]

And you have to be an ATCO at least as cool as John Cusack or Billy Bob Thornton ;)

On a serious note, I suspect Heathrow Director or Gonzo will be along shortly to help you :ok:

[Scuzi]

As well as walking on water and feeding thousands with a few fish and a loaf, Heathrow controllers can compress time into what is know as the "Heathrow Minute".

[HEATHROW DIRECTOR]

Oh yes.... 31 seconds!

[ZOOKER]

Spitfire,
notwitstanding the fact that the southerly runway at Manchester is hardly ever open these days, bear in mind the following:-

On westerly operations at manchester, all departures have to cross the landing runway to get to the departure runway.
On easterlies, all landed traffic has to taxi across the runway being used for departures.
This is not ideal and inevitably slows the movement rate down. It does not happen at Heathrow, but some crossings do occur there due to the terminal geography.

Prior to the introduction of the second runway at Manch, 54-58 movements per hour was often achieved. i believe the record stood at 60 for some time.

[cossack]

i believe the record stood at 60 for some time.
That was a fun hour. 28 arrivals and 32 departures IIRC. :cool:

Adding the second runway did not bring forth as many advantages in moving aircraft as you would imagine. Nearly all departures from 24L followed the same initial route (due noise abatement) and so there was little use made of the "Manchester minute" which for some reason had to be 60 seconds. The "Manchester 2 minutes" was used a lot though, and it, unsurprisingly had to be 120 seconds. 117 seconds was apparently not enough.:rolleyes:

[Gonzo]

Without wishing to get all defensive:eek:, the so-called Heathrow minute is just the use of Reduced Separation in the vicinity for departing aircraft which any airfield can do depending upon the tracks of those aircraft. For example, on easterlies a MID followed by a DVR is 2 minutes as specified in the MATS Part 2, but yesterday were being launched 'wheels up' which if they're both Medium category aircraft can be as little as 45 seconds. Visually separated until 3nm apart and diverging.

[Spitfire01234]

Thanks for your informative replies!

I have two additional questions:
How are the arrivals separated under VMC?
Does Heathrow use the usual 2,5/3nm radar and the wake vortex separations?

[HEATHROW DIRECTOR]

<<Does Heathrow use the usual 2,5/3nm radar and the wake vortex separations?>>

Yes but weather conditions can play a part in the final approach separations. VMC separations cannot be used in Class A airspace. Occasionally, under certain prescribed conditions, both runways may be used for landing. If the weather is good, reduced separation may be used when pilots can see other aircraft on final approach.

[Gonzo]

The arrivals are separated by either the required wake turbulence minima, or if no wake turbulence applies then the usual spacing for arrivals is 3nm applied to 4DME, which is about 2.5nm at touchdown. If we have a decent headwind, and good visibility, we apply 2.5nm radar sep to 4DME which means 2nm at touchdown visually separated.

[NotaLOT]

Heathrow is not unique, Copenhagen handles in the region of 80-90 movements per hour using two runways separated by not much more than 600 m (but significantly staggered). There are three runways in total, but the crosswind is only used when it's REALLY windy.

[HEATHROW DIRECTOR]

EbonyGrove. When I worked at Kidlington in 1970 we achieved very high movement rates, far in excess of Heathrow. But there is a great deal of difference between a sky full of VFR clockwork mice and a sky full of IFR commercial jets!

[Howabout]

Spit, Good on you - I wish you success with your thesis.

Other posters: please feel free to shoot me down - I don't want to give a young lad/lass a bum steer, and there are plenty out there with a damned sight more knowledge than me. But, for what it's worth, and in my experience, as follows:

In a 'standard' environment, an airfield with one runway handling a normal mix of traffic; turbos, medium jets and heavies can safely accommodate 40 movements per hour.

That's a real basic stat Spit, but holds true in my experience.

We then have the added levels of complexity, as alluded to by some of the brains on this thread - parallel runways, distance between runways, high-speed turn-offs, noise abatement; the list goes on. Some of these factors contribute to increased capacity, others hinder it.

The problem in 'modelling runway capacities' is that there are so many variables. And don't discount the political as regards noise abatement, which includes the politicians insisting on 'noise-sharing' that inhibits the ability of the coalface (the controllers) to move more traffic than they actually can.

Writing a thesis on this stuff, Spit, is a real challenge. Where to start and not tie yourself up in knots? How does one write a tight paper that is logical and flows?

My advice is to start with the basic stat (40 movements per hour for a single runway), then discuss variable by variable the factors that influence capacity - parallel runways etc. That will give you some structure and a starting point. You can then identify section by section those factors that increase and decrease capacity. Even then, the variables will overlap - it's a complex environment and there are no absolutes.

To the brotherhood reading this, I am prepared for incoming and have retreated with a Merlot.

Good luck Spit!

[Brian 48nav]

Does 'C' Watch's record total of 98 in one hour (followed by 90 and 89 in the next two hours), achieved in Summer '99 still stand?

Ask Suzy and Mike nicely and they'll tell you all about it!

Nothing compared with 60/hr single runway eh' Manch'?

[airsmiles]

I just wondered if movements may also become limited due to high cross-winds and the fact that the old 23/05 runway(s) is/are no longer available? I realise 23/05 was only used very infrequently but can an excessive cross-wind affect the movements per hour?

[Dan Dare]

Not just crosswind, but headwind!

Picture an aircraft flying 160 kt to 4 nm. In an hour there could be 160 nm of arrivals spaced at 3 nm giving approx. 53 arrivals in an hour if spacing is accurate and no wake turbulence requirement exists. Now put in a mere 10 kt headwind component (at 2000 ft) gives a ground speed of 150 kt and only 50 arrivals. 30 kt headwind aloft would suggest fewer than 44 per hour!

Throw in variations of spacing and a few A380s an hour and you can see why they "only" achieve scheduling of forty something and hour.

A single runway operation can reduce delays in wind by reducing the (non-vortex) spacing to take account of the extra time between arrivals: nil wind and 7 nm required between arrivals to facilitate a departure you should manage 23 arrivals and 23 departures. If the wind increases the space required reduces so the same runway utilisation could be achieved in a 35 kt wind and 5.5 nm spacing.

[055166k]

Don't concentrate too much on Heathrow....have a look at Gatwick who are the absolute masters of single runway operations. A comparison of peak Gatwick performance on a single runway far exceeds Heathrow's two runway equivalent. Airport design has a big impact on movement efficiency. Do some reading to brief yourself.....look at the UK AIP [google...then open IAIP]...find London Heathrow and look at the layout.....look at London Gatwick. Buy an anorak and go and watch how it all works. Don't laugh....that's how I started in the job.

[Musket90]

In addition to the runway crossings mentioned by Zooker in Post 7 Manchester's departure routes, for environmental reasons, are not particularly good for capacity with many consecutive departures requiring longer separation intervals. Also the taxiway and stand infrastrucure could not cope with capacity levels achieved at Heathrow without getting totally clogged up. So to achieve the best capacity out of two runways you need the whole airport infrastructure and ATC procedures to be designed to match it.

[DaveReidUK]

A comparison of peak Gatwick performance on a single runway far exceeds Heathrow's two runway equivalent.To be expected.

Heathrow operates for most of the day in segregated mode (takeoffs on one runway, landings on the other).

Gatwick, of course, operates its single runway in mixed more, interspersing takeoffs and landings, which in itself increases runway movement rate.

[HEATHROW DIRECTOR]

<<Gatwick, of course, operates its single runway in mixed more, interspersing takeoffs and landings, which in itself increases runway movement rate.>>

??????????????????????

[055166k]

Pprune buddies are correct. Your analysis might show that Heathrow does not have a capacity problem......only an operating problem. A third runway won't help much either and for your project you might examine the need for an additional runway against the under-used capacity of the two that are already there. You have to think "outside the box".
Here is a little something to think about on a slightly different topic.....If the ILS glidepath angle was increased by half a degree it would save a billion tons of CO2 and cut noise by half [I made that up, but official reports can be written to promote any pre-conceived outcome.....beware....think for yourself.....let us know what you think]
By the way, if you want to see slick operations you need to go and watch military ATC. The mil guys are experts at their craft. When there were F 1-11's at Upper Heyford I watched 73 get airborne in 35 minutes for exercise Salty Hammer 86.......and when they returned they were all on the ground in well under an hour.

[DaveReidUK]

??????????????????????Which part are you questioning, Brendan, the bit about Gatwick only having one runway, or that segregated mode produces a lower movement rate per runway ?

[Spitfire01234]

Thank for your great hints from the practical point of view!

I have another question concerning the appliance of the wake vortex separations:
When will the wake vortex separation be used? The manual of the German air traffic control says the follwing:

"...
328.3 The [wake vortex] separation minima mentioned above do not need to be applied, if :

-.31 the pilot of an aircraft has declared that he has the preceding aircraft in
sight and will attend to an appropriate distance himself;
- .32 the pilot of an aircraft renounces wake turbulence separation;
- .33 the area within which wake turbulence is expected will not be penetrated.”

Does this mean that in bad weather conditions (IMC) the wake vortex separation has to be applied always, under VMC the separations don't have to be? Is it the more frequent case that WVS is not in use?

[HEATHROW DIRECTOR]

Dave. I just do not understand the suggestion that a single runway could move more traffic than two runways. Heathrow is effectively two airfields - one for departure and one for arrival. Are you suggesting that if just one runway was employed the movement rate would increase? There are lots of other factors to consider. I worked Heathrow Tower for 20 years but know little about Gatwick, for example, where a high rate is achieved on one runway. How much crossing traffic does Gatwick have, for example? Heathrow's southern runway is constantly being crossed by traffic.

[chevvron]

My personal record for runway utilisation was at the PFA Rally at Cranfield one year; at one point I had 7 on the runway and another 14 on final - but they were all VFR of course!!

[Talkdownman]

HD, I think with SRO, as at KK, (and eg. 6nm spacing) a higher utilisation rate is achievable by shooting the gaps with air movements (instead of crossers!). The problem at LL is that mixed mode provides FIN and DEP IFR separation issues because the runways are just too close together for high intensity and literal parallel ops (ie. rather than staggered parallels).

(I used to love SRO when working with a decent Air Movement Planner and the challenge of 55/hour...I doubt that what we did would be allowed now...!)

[DaveReidUK]

Dave. I just do not understand the suggestion that a single runway could move more traffic than two runways.But that's not what I said.

I was referring to the movement rate per runway.

segregated mode produces a lower movement rate per runwayHeathrow's two runways obviously have a greater total capacity than Gatwick's one, but the individual arrival and departure runways each have a lower movement rate (because you're not slotting departures in between the arrivals, and vice versa).

Sorry for any confusion.

[HEATHROW DIRECTOR]

Yes, M. I used to love SRO too. When I started there we'd have runway re-surfacing almost every year (or so it seemed) when we'd be SRO for 6 weeks. I think JK (No 2) and MR (Air) produced some extraordinary total in one hour but I'd rather not think how they did it! Didn't Rambo do a "big" hour once? My brain is like sawdust now so I can't recall the details.

[055166k]

Pprune buddies have hit it right on; if you think of Heathrow as effectively "two airfields" it does not handle double Gatwick movements by a big margin.
I back the Boris plan.......look at Hong Kong!!!! You need the one thing Heathrow can never have...SPACE. Compare the size of the Heathrow site to Paris CDG or Amsterdam....its like a football field by comparison.
Get away from the draconian operating restrictions that strangle Heathrow growth.....build another bigger airport.....unleash ATC and show how much traffic can be shifted.

[Howabout]

What a great bloody thread! I am sure the young fella/lass is getting something out of this. Nice to see such well-mannered and thought-out-responses. Of course, the brotherhood has always been superior in that regard (generic term that includes our sisters as well). It's all a good read.

Spit, don't over complicate the mission in respect of 328.3 and get 'too far down in the weeds' to start off with. These are the exceptions rather than the rule. You will find that similar exceptions exist the world over.

However, and just again in my experience, at a major airport the exceptions make little difference when dealing with passenger-carrying traffic; and, hence, basic capacity. I can't recall a single PIC of a large passenger-carrying aircraft waving ATC wake-turbulence separation minima (wake-vortex minima in your language) and take the responsibility. My experience may be different from others on that point but, in general terms, the pilots take what ATC tells them on this one.

In my view 328.3.31 can be a little misleading. The procedure in this country is 'sight and follow.' But I doubt you'd find a controller worth his salt that would assign a 'sight and follow' in a situation where the wake-turbulence standard would be compromised with RPT (regular public transport).

Consequently, I believe that in respect of your thesis wake-turbulence is a secondary issue. Not with respect to safety, but with respect to an overall postulation on runway capacity.

I'd suggest an 'addendum' to the effect that 'odd instances of pilot acceptance of responsibility for wake-vortex separation do not significantly influence runway capacity,' or something similar.

I will now retreat to the bunker after having cracked a very good Chardy and put the the tin-hat on.

[Gonzo]

By definition, SRO will get you more than segregated. However, get the right mix on a good day and you can easily get a 55 departure hour.

Trick is to have 5 airborne and painting on radar within the CTR boundary! :}

[HEATHROW DIRECTOR]

<<By definition, SRO will get you more than segregated.>>

Sorry, I don't get that at all. Maybe they ought to close 27L and just use 27R - no crossers to worry about. Are you seriously suggesting that this would improve the movement rate?

[cossack]

I think what he's getting at here WRT segregated vs SRO is that there is less "dead time" on a SRO than there is with a segregated operation. If every aircraft was a 737 then all would be great but there are "heavies" which eventually need a wasted gap behind them which can be "filled" with and arrival in SRO.

<opens old can of worms>
Dual mixed mode ops at LHR anyone. 55/hour both sides?;)

[Gonzo]

HD, I mean all other things being equal, one runway operating in SRO will have more movements than one segregated mode runway, albeit if the fates (and SID splits etc) align you could approach SRO movement rates with a departure only runway.

SRO runway, mid 50s?
Usual departure only runway, mid to high 40s?
Arrival only runway, low 40s?

I'm not comparing SRO with a two-runway airport operating in segregated mode.

I say by definition because with SRO you effectively negate vortex.

[Brian 48nav]

Apologies for us retired old farts hijacking your thread, But...

HD

I can remember once on GMP with a trainee we had about 12-15 minutes start up delay. Rambo arrived to take Air Deps so I said to the u/t 'start em' all up','Why?' he said. I replied,'Just watch this guy, he'll run out of aeroplanes unless you keep up!'.

Ah, JK, how many were cleared for take off at the same time?

On our 98 day, there were 52 deps and 4 landers on 09R and 42 landers on 09L. Hobbsie was Air Deps and I think JB was No2 over at TC.

Mind you Rambo and SH should have been good at Deps as they seemed to spend all their time on there or GMC!

[Talkdownman]

I think I'll change my handle to 'Messerschmitt'.... :}

[chevvron]

Messerschmiitt used to make a bubble car; I can see the resemblance.

[On the beach]

DelayReducer

"If you're strictly looking at runway capacity the real theoritcal stats you need are:

Occupancy Time
Arrival Separations
Departure Separations
Line-up times
Wake Turbulence Mix

They are the fundamental drivers".

I think you will find that the "fundamental drivers" in the "real non-theoretical" world, where most of us work, are:-

1. The number and positioning of RETs.

2. The training of the other "fundamental drivers", (i.e. those at the pointy end) in the use of those RETs at the speeds they were designed to be used at. That's down to the Check Captains of the airlines involved, ensuring that their line pilots understand how this affects their and every other airlines "on-time" operations.

Arrival separations are written in stone, until Mr. Airbus and Mr. Boeing get their act together and learn how to design planes that don't create wake turbulence.

Departure separations, same as above, direct your complaints to the perpetrators of wake turbulence. Controllers just have to adapt to aircraft manufacturers shortcomings and make their mistakes work.

Line-up times. Generally not a problem in mixed mode. You can't clear one to take off until the lander has cleared the same runway. And if they are that slow that they can't get into position and spooled up ready to roll the instant that the lander is clear, then they won't be flying out of your airport unsupervised for much longer.

"Wake turbulence mix". Now that is something that ATC can and do, subject to traffic, influence. A "medium" should always be ahead of a "heavy" if the two are arriving at the same time and conversely, a "medium" should always depart ahead of a "heavy" . Sadly, life isn't quite so simple and increasingly "heavies" outnumber "mediums" at major airports.

And that, my friend, is why the world needs Air Traffic Controllers.

On the beach

[Howabout]

Hey, on the beach, very amusing as regards grammar. Hadn't heard that one.

Not all abbreviations are universal. Despite having done Tower, Approach and Area over a number of years I have no idea, over this side of the world, what 'RETs' stands for.

As this is primarily a thread to give a young person some advice, can you give us that one in plain English?

Thanks.

[Fesch]

RET = Rapid exit taxiway
I agree with on the beach. The lack of RETs is extremely influencing the landing rate at our airport.

[Norman.D.Landing]

Rapid Exit Taxiway

Rapid Access Taxiway

Commonly referred to over here as RET's and RAT's.

:ok:

[HEATHROW DIRECTOR]

It's all yuckspeak. In my day they were simply Fast Turn-offs.

[Howabout]

Thanks,

Appreciate the advice. Regards.

Yep, HD, we refer to them as 'high-speed turn-offs.'

[N90-EWR]

We also call them high speed.

[DaveReidUK]

Rapid Exit Taxiway

Rapid Access Taxiway

Commonly referred to over here as RET's and RAT's.I'm struggling to think of an instance of a Rapid Access Taxiway at a UK airport - although of course all RETs are RATs when the wind is in the opposite direction. :O

Google doesn't help much: only 63 hits overall for RAT compared to 11,000+ for RET.

[2 sheds]

It's all yuckspeak. In my day they were simply Fast Turn-offs.
Yukspeak for good reason, though, HD - fast turnoff/first turn-off?

2 s

[HEATHROW DIRECTOR]

2 sheds. I wasn't referring to phraseology. That's what they were referred to at other times. On the R/T at Heathrow turn-offs were described by the appropriate block number.

[RAC/OPS]

Rapid exits in Melbourne. Some pilots not very rapid using them though!