Heathrow Approach Path

[krsmith]

13 October 2013
From Kevin Smith, SW14

Can someone explain how flights bound for Heathrow Airport are marshalled? I live directly beneath an approach path to one of Heathrow’s two runways so I must declare a personal interest.

East Sheen is 12 miles due East of Heathrow’s Southern runway. So I have had plenty of time to observe both the precision with which incoming flights can pass line astern over the same two or three houses then migrate a little further north to give some respite from the noise. This modest transition is quite apart from, runway rotation.

But a colleague assured me that I was mistaken and that all aircraft overflying Sheen are already aligned with the southern runway. So to settle the matter, I contacted the Heathrow press office while he contacted a professional pilot. They both stated that planes landing at Heathrow were aligned with the runway centerline when they passed over Sheen.

But Heathrow’s recent ‘noise respite trial’ surely depends on the ability to direct incoming flights around the two noise relief zones terminating in neighbouring Putney? So I searched the Internet for a possible answer and found that the ILS localiser, used to guide aircraft in the end of the runway, projects a fan-shaped beam with an azimuth angle of five degrees at its apex.



At Sheen, 12 miles from Heathrow, the localiser beam would have a lateral spread of one mile (2π12 miles x 5/360) and this fits with what I see. Early morning flights often take a southerly route bordering Richmond Park, then later flights are moved to just north of the Upper Richmond Road. I have often tracked this transition while walking from my doorstep to the Upper Richmond Road.



So can you clarify the matter for us? Does Heathrow’s set a specific ILS azimuth approach for incoming flights? And if so, how are navigational systems such as VOR and Satnav used to turn flights into the ILS beam at the right point? I reckon a couple of pints at the Hare and Hounds are resting on the answer – but who will be buying?
Kevin Smith

[DaveReidUK]

But a colleague assured me that I was mistaken and that all aircraft overflying Sheen are already aligned with the southern runway.He is correct. You are mistaken.

They both stated that planes landing at Heathrow were aligned with the runway centerline when they passed over Sheen.They are correct. Aircraft are required to join the ILS at or above 2500 feet (3000 feet at night). That means that they must be on the runway centreline by around 8nm from the runway during the daytime - roughly by the time they are over Putney.

But Heathrow’s recent ‘noise respite trial’ surely depends on the ability to direct incoming flights around the two noise relief zones terminating in neighbouring Putney?The "no-fly" zones made little or no difference to the flightpaths of aircraft by the time they had reached Putney.

Does Heathrow’s set a specific ILS azimuth approach for incoming flights?If you mean "is the ILS offset from the centreline of the runway?", the answer is No.

I reckon a couple of pints at the Hare and Hounds are resting on the answer – but who will be buying?Looks like the drinks are on you.

[MarianA]

the ILS localiser, used to guide aircraft in the end of the runway, projects a fan-shaped beam with an azimuth angle of five degrees at its apex.
That five degree fan is the area in wich the localizer signal can reliably be received by the equipment on the aircraft. The target then is to fly down the centre line of that fan, any deviation from that will show in the cockpit and be quickly corrected.

The direction of that transmitted centreline is fixed at installation of the system and in the majority of cases it is pointing down the extended centreline of the runway the system is guiding aircraft to. ILS systems can be installed at an angle from a runway, but that is only done where terrain or other obstructions require it and that offset-angle is then fixed as well and cannot be changed without physically moving and realigning the antenna-array.

In theory it would be possible to instruct crews to fly the localizer at a constant deflection of x and thus follow not the line the transmitter is pointing at but come in at a slant. I believe that is never done.

You would need multiple ILS system installation to the same runway to achieve any noticeable spread of flight paths at that stage. That is never done either.

[HEATHROW DIRECTOR]

<<Early morning flights often take a southerly route bordering Richmond Park, then later flights are moved to just north of the Upper Richmond Road>>

I suspect that what you are seeing are aircraft landing on both runways, which may occur under certain conditions during early morning.

<< how are navigational systems such as VOR and Satnav used to turn flights into the ILS beam at the right point? >>

All aircraft flying into Heathrow are radar controlled. Instructions from ATC include changes of heading, speed and altitude and the position at which aircraft join final approach varies greatly depending on traffic. It may be 8 miles or it may be 15 miles. To achieve the maximum landing rate, speed control is applied on final approach until aircraft are about 4 miles from the runway.

HTH

[c52]

I have a dozen questions I'd like to ask on this topic - surely there's a book available to explain it all. Anyone got any ideas? The best I can find is from Ian Allen, published in 1998.

[Talkdownman]

Have a little play with Heathrow Webtrak (http://webtrak.bksv.com/lhr). That will show you where all the planes have been. Then you can see just how skilled Heathrow Directors have to be...

Allow a little time for it to load. Have fun!

Oh, and Kevin, mine's a pint of Doom Bar...Cheers!

[c52]

It's from watching FR24 that my questions arise.

[Gonzo]

c52, ask away....

[c52]

here's a few...

why do most flights get to LHR via Lambourne when most of the world is not to the north-east?

why are there days (with decent weather) when all the stacks are full for hours on end and other days when holding is the exception?

why do some US/Canada/Dublin flights arrive via Ockham?

why would two consecutive flights to Singapore turn right and left on leaving LHR?

how much disruption is caused by the 1500 runway swap, and how much when the runway changes from 09 to 27 or vv?

when LHR's capacity is stated as 498000 movements per year (I think), how is that calculated? Not on the basis of an arrival and a departure every minute from 06:00-23:00.

Why do aircraft fly Biggin-Epsom-almost back to Biggin before lining up with the runway? It makes for a lot of unnecessary noise and pollution over London and I've have thought the purpose could be served just as well by flying out east until it's time to turn onto the approach.

Why do some planes cross the centreline on their approach - e.g. Ockham to ~Edgware?

Do aircraft flying to say Farnborough or Biggin Hill have a sort of dedicated tunnel to fly through, or are they directed to avoid whatever other traffic is around at the time?

Most Detling departures fly past Biggin at < 8000', but a few are well clear at 10-12000'. Couldn't they all get that high to avoid inbound traffic?

The first time I took off on 09R at Heathrow we were warned we'd be making an extremely sharp right turn immediately after take-off for noise abatement reasons. That duly happened - but they don't do it now. Why not? (It was a MAS 747).

[HEATHROW DIRECTOR]

Over to you Gonzo. You've done it now!!

[Hartington]

The first time I took off on 09R at Heathrow we were warned we'd be making an extremely sharp right turn immediately after take-off for noise abatement reasons. That duly happened - but they don't do it now. Why not? (It was a MAS 747).

Not related to Heathrow but some years ago I was on a United 777 from San Francisco to London. UA have the ability to pipe the ATC into channel 9 on the IFE and I was listening as we taxied out. As we approached the runway the controller asked "can you accept a shorline 9 departure" to which the answer was an immediate "yes" followed by ATC asking "are you sure". There was then a delay before our pilots once again said they could accept the departure. We lifted off and immediately turned right; the normal long haul departure from 28R back to London being straight over the peninsular to the ocean and then a right turn.

The point is that just because you haven't experienced the same departure as the MAS one since it happened doesn't mean it never happens.

[Defruiter]

I can answer some

why do most flights get to LHR via Lambourne when most of the world is not to the north-east?

Traffic doesn't just route via LAM from the North East. Anything coming from the east of Heathrow tends to come in via LAM. (Holland, Belgium, Germany, eastern block, Russia, Scandinavian countries, the far east etc). BIG traffic tends to come in from parts of France/Spain, Italy, Africa and other countries to the south east. OCK traffic tends to come from over the pond, parts of France/Spain, South America. BNN traffic tends to come from across the pond and UK domestic destinations.

why are there days (with decent weather) when all the stacks are full for hours on end and other days when holding is the exception?

There are lots of factors. Could be due to weather, airline schedules, atc staffing, the list is endless.

why do some US/Canada/Dublin flights arrive via Ockham?

Over the atlantic ocean are a series of tracks, called NAT tracks. As there is no radar over the ocean, aircraft must fly on these prescribed tracks at certain altitudes, several minutes apart. The tracks tend to be aligned with the wind. If the jet stream is further north, the tracks are northerly (so the planes have the wind behind them when coming east bound). if the jet stream is to the south, the tracks are southerly. So when tracks are northerly, aircraft tend to come in over scotland and down the UK into BNN, and when they are southerly, aircraft tend to come in over Wales and the South west into OCK.

why would two consecutive flights to Singapore turn right and left on leaving LHR?

Depends on the route that they have planned to fly. There can be lots of different routes to get to the same place. Airlines will plan on the best route for that aircraft on that particular day, taking into account lots of factors such as weather conditions, fuel required, aircraft weight etc. The aircraft turning right off 27s (left off 09s) is leaving UK airspace via Clacton, the aircraft turning left off 27s (right off 09s) is leaving UK airspace via Dover.

how much disruption is caused by the 1500 runway swap, and how much when the runway changes from 09 to 27 or vv?

From a radar point of view, switching from 27L to 27R or vice versa causes very little disruption, if any. The only complicated bit is working out which aircraft is last/first on either runway. When switching from 09 to 27 or vice versa, things can get very complicated. I don't know what disruption is caused on the ground, I'm not a tower controller. Someone else will have to answer that.


Why do aircraft fly Biggin-Epsom-almost back to Biggin before lining up with the runway? It makes for a lot of unnecessary noise and pollution over London and I've have thought the purpose could be served just as well by flying out east until it's time to turn onto the approach.

It's all to do with the set up of the airspace. Heathrow isn't the only airport in London.

Do aircraft flying to say Farnborough or Biggin Hill have a sort of dedicated tunnel to fly through, or are they directed to avoid whatever other traffic is around at the time?

They fly on prescribed routes, which keep clear of other airports traffic (to a degree!)

Most Detling departures fly past Biggin at < 8000', but a few are well clear at 10-12000'. Couldn't they all get that high to avoid inbound traffic?

Unfortunately not. All aircraft climb at different rates. We have to ensure that planes are kept either 3 miles or 1000ft apart. A lot of the time, there just isn't the room to get them going up and away from the inbound aircraft, so they are stuck low down.


I'm sure others will chip in with ones I've missed, or to add more content :)

[DaveReidUK]

And a few more:

why do some US/Canada/Dublin flights arrive via Ockham?As far as transatlantic arrivals concerned, their routes over the ocean (the NAT tracks) very from day to day depending on the winds - some days they are much further north/south than other days, which will affect where they enter UK airspace and therefore which approach routing (STAR) they arrive at Heathrow via (i.e. Ockham or Bovingdon).

Bear in mind also that the USA and Canada are very large countries. If you look on a globe you can see that the Great Circle route from West coast points such as San Francisco and Vancouver goes much further north that the GC routes from, say, New York or Boston.

The first time I took off on 09R at Heathrow we were warned we'd be making an extremely sharp right turn immediately after take-off for noise abatement reasons. That duly happened - but they don't do it nowBut they do.

Whenever Heathrow is operating on easterlies, departures are normally from 09R, and when the NAT tracks are southerly (see above), departures to the USA will usually head out over South Wales, which involves a 180 degree right turn on departure onto the Compton SID. Gonzo and/or HD will explain the challenges that ATC face keeping those departures clear of inbounds coming off the stacks, which results in around two-thirds of 09 CPT departures going technically "off-track".

Look at WebTrak for last Friday (11 October) from 16:30 and you will see half a dozen successive departures to YUL, EWR, ATL, LAX, BOS, JFK) doing just that - and note also the two SAN and YEG departures that turn left after takeoff and head north.

This is worth a read:

http://www.heathrowairport.com/static/Heathrow_Noise/Downloads/PDF/Departures11.pdf

[Defruiter]

09 CPT departures don't fly the SID at all (Though there may be occasions when they do, but these are few and far between.) They get airborne on a heading. They conflict with the arrival stream. If they followed the SID, they would almost be flying backwards up the ILS. Apparently, they've been trying to change this SID for 20+ years...

[DaveReidUK]

09 CPT departures don't fly the SID at all (Though there may be occasions when they do, but these are few and far between.)Well around a third of CPT departures from 09R are classed as "on-track", which means that they have stayed within the NPR lateral swathe that extends 1.5km either side of the SID track.

[DaveReidUK]

One more:

how much disruption is caused by the 1500 runway swap, and how much when the runway changes from 09 to 27 or vv?The first part has already been answered. Changing ends, from easterlies to westerlies or vice versa, typically involves a gap of around 8 minutes between the last landing in the original direction and the first in the opposite direction.

Again, if you want to see an example on WebTrak, look at last Saturday evening (12 October) from 17:25 onwards.

[Gonzo]

Well, that was easy.

Next?

[DaveReidUK]

Last one:

when LHR's capacity is stated as 498000 movements per year (I think), how is that calculated? Not on the basis of an arrival and a departure every minute from 06:00-23:00.The limit of 480,000 ATMs per year is a planning constraint dating from the T5 decision. Here's how it works:

http://www.acl-uk.org/UserFiles/File/LHR%20Local%20Guideline%203%20v2.pdf

[HEATHROW DIRECTOR]

I think they call it "thread drift" Gonzo!

[HEATHROW DIRECTOR]

<<Changing ends, from easterlies to westerlies or vice versa, typically involves a gap of around 8 minutes between the last landing in the original direction and the first in the opposite direction.>>

8 minutes? What's going on? When I was there we'd have been shot for that.

[DaveReidUK]

I think they call it "thread drift" Gonzo!

"Off-track", so to speak. :O

[Talkdownman]

After some dodgy bits of opposite-end engineering ISTR we settled for first opposite ender to be at 10D at time of last departure. That's nearer 5 minutes. A good time for a tower handover...

Why do aircraft fly Biggin-Epsom-almost back to Biggin before lining up with the runway?
This is the classic path-stretch 'dumb-bell' tool to position the downwind traffic in a staggered combined downwind sequence (merging the two down-winds). Have a closer look at Webtrak.

Why do some planes cross the centreline on their approach - e.g. Ockham to ~Edgware?
This another classic tool out of the box when one has too many off the stacks. It also might prevent someone turning back into the hold when they don't really need to. Or if one is in an indecisive or cavalier mood. There weren't too many rules on how to do it back in '93, anything went to make it work. I expect the SMS yellow-jackets have changed all that. But, as HD would agree, it was fun...

[DaveReidUK]

8 minutes? What's going on? When I was there we'd have been shot for that.In fairness, I should add that the gap between opposite end departures, as opposed to arrivals, appears to average out at around 4 minutes. In fact it's a few seconds less than that in the 12/10 WebTrak example that I quoted.

[c52]

Interesting, and to some extent, less than persuasive. If the whole thing were redesigned today on a blank sheet of paper, would the result look broadly similar or rather different? (Assume LHR doesn't get redesigned).

[DaveReidUK]

Interesting, and to some extent, less than persuasive.I don't see anyone trying to persuade you about anything. :O

If the whole thing were redesigned today on a blank sheet of paper, would the result look broadly similar or rather different? (Assume LHR doesn't get redesigned).Well knocking it down and starting again (in the same spot) isn't an option. As any newspaper will tell you, the scenarios being considered range from bolting on one (or possibly two) additional runways outside of the current airport perimeter, or starting again somewhere else.

Not really relevant to this thread, but discussed at length here:

http://www.pprune.org/airlines-airports-routes/200585-heathrow.html

and here:

http://www.pprune.org/airlines-airports-routes/469575-new-thames-airport-london.html

[c52]

I can't have been clear enough.

ISTM a flight from anywhere SE of London should arrive via Biggin, not Lambourne. I don't understand why that shouldn't be the case. I asked "why" and I was told that *is* the case.

And I meant to ask, what if all the ATC were redesigned for today's traffic while LHR stays as it is.

Thanks.

[Navy_Adversary]

When my Eva Airways flight from BKK flies over the Antwerp area heading towards Clacton what freqs would the crew use before contacting LHR approach? TIA

It is 1915 hours arrival and we usually have to hold at Lambourne for 10-15 minutes, sometimes going to a 09L but more often 27L, some great views of dear old London Town if the weather is good, even though it is dark.:)

[DaveReidUK]

ISTM a flight from anywhere SE of London should arrive via Biggin, not Lambourne. I don't understand why that shouldn't be the case. I asked "why" and I was told that *is* the case.OK, I understand your confusion.

The following is a gross over-simplification, but here goes:

Firstly, if Heathrow could function with 3 holding stacks instead of 4, it would only have 3 - but it can't, that's why the current 4 stacks have existed for many years.

Yes, it might be more logical for a higher proportion of arriving flights to use BIG instead of LAM, but to understand the reasons you really need to look at the airways structure that feeds into both holds.

If you don't have access to any hard-copy maps, look at skyvector.com and select high-level routes, then find two intersections named LOGAN and ALESO. Again, it's an over-simplification, but those are two of the main "funnel" (not a technical term) points that feed into the LAM and BIG holds, respectively.

Then look at the airways that lead to those funnel points. Very roughly speaking, flights arriving from, or over, Belgium, Germany and all points southeast/east/northeast of those countries will route to LOGAN via the airways marked UL610, UL980 or UP7 and thence to LAM.

Flights arriving from France, or over France from Switzerland, Italy, the Med, etc, will route to ALESO and then to BIG, to hold there if necessary.

Bear in mind also that BIG and LAM are less than 20nm apart, so in terms of the track distance flown on a 5000nm, or even a 500nm, route it makes very little difference overall, so that isn't really a consideration in the distribution of incoming routes between the stacks.

I hope that makes sense. No doubt by now our ATC colleagues will be throwing up their hands in horror at the factors I have omitted or misrepresented, but that's my story and I'm sticking to it. :O

As well as the charts on skyvector.com, it's worth visiting the NATS AIS website, NATS | AIS (http://www.nats-uk.ead-it.com). If you click on IAIP, then on Aerodrome Index - Specific, you can find the Standard Approach Routing (STAR) charts for Heathrow/LAM and Heathrow/BIG.

[Gonzo]

c52,

LAM - most long haul flight from the far east and many from hte middle east use LAM. This is mainly due to the great circle routes. Without wishing to appear teach you to suck eggs, a straight line drawn on a two dimensional map does not represent the shortest route; you need to use a globe. Flying from Singapore to London takes you up over Russia and approaches London from the north east.

Also, many flight from northern Europe, Germany, Belgium, The Netherlands etc arrive at LAM. Dover is one of the more busy sectors of airspace, so it doesn't make sense to force everything through to the 'nearest' holding stack; that would just cause undue delays as flow control would result in ATC slot delays. Flows around Europe are designed to be 'spread out' to allow more aircraft to fly. This is not just an LHR issue, it occurs at most major airports in Europe.

[HEATHROW DIRECTOR]

I presume stack switching still happens? That means when there is a lot of traffic offering for a particular hold the STAR is changed and the aircraft routes to one of the other holds which is less busy. This has happened in recent days with traffic from the north re-routeing to OCK. I have known traffic destined for LAM to be re-routed to BIG or even OCK.

Now we have someone asking for frequencies!

[c52]

DaveReid, that is very interesting and I'll have a look at that stuff when I'm not supposed to be working.

I hadn't really grasped that it's only an extra 20 miles to go to one hold rather than another, and they'd probably just have to do an extra loop if they saved those 20 miles.

I do notice planes at Biggin that have crossed the coast north of Southend. It seems to happen most at 1500, which is why I asked about disruption caused by the runway swap.

[Gonzo]

c52,

Have a look here, and you can see the general flow into/out of the SE of England.

http://www.londonairspaceconsultation.co.uk/wp-content/uploads/2013/09/LAC_Appendix_C_SE_Eng_Air_Traffic1.pdf

....page 4 onwards. Page 4 shows only LHR traffic, dark blue is outbound, light blue is inbound. You can see the organisation of routes quite clearly, and how they are deconflicted.

[HEATHROW DIRECTOR]

<<I do notice planes at Biggin that have crossed the coast north of Southend. It seems to happen most at 1500, which is why I asked about disruption caused by the runway swap.>>

I haven't been following this thread but noticed your last post. There is no relationship between the runway alternation procedure and the numbers of aircraft arriving from a particuloar direction. The alternation causes no disruption at all as final approach spacing is maintained throughout. A runway change to the opposite end can cause short delays but, again, they should not be more than a few minutes. I say all this with the background of 31 years as a Heathrow radar controller.

Aircraft arrival times are dependent on so many variables one cannot lay down precise details. Wind is a significant factor - a strong wind on final approach can seriously reduce the landing rate and before flow control is established, stack swapping may take place. And a million more reasons....

.

[Wycombe]

An unusual I remember from a few years ago.....a stormy evening with CB's all over the Terminal Area, and a rather inconvenient one right over OCK.

The OCK hold was moved to CPT (Compton)! I live out that way and this was the only time I'd ever seen inbounds stacking over what is usually an outbound/en-route beacon.

[DaveReidUK]

Interestingly, there is provision in the AIP for LHR traffic inbound to OCK to use the hold at OKESI (about 3 miles ESE of Chippenham) during periods of congestion in the London TMA.

The hold is just off the western edge of the map on the STAR plate.

[Peter47]

Going back to some of the earlier posts, does a 5 degree ILS scan cause problems in strong headwinds? I remember the one and only time I got to be on the flight deck for a landing (nearly twenty years ago) and there was a strong crosswind and I it appeared that we came in at an angle of more than 5 degrees to the runway (although that may have been an optical illusion) or do pilots have to rely on a visual approach in such circumstances?

[DaveReidUK]

there was a strong crosswind and I it appeared that we came in at an angle of more than 5 degrees to the runway (although that may have been an optical illusion)It was indeed an optical illusion. The aircraft travels along the ILS centreline, but in order to do so in a crosswind the direction it points in is offset.

[HEATHROW DIRECTOR]

<<The OCK hold was moved to CPT (Compton)! I live out that way and this was the only time I'd ever seen inbounds stacking over what is usually an outbound/en-route beacon.>>

Yes.. when things get really scary the holds are moved all over the place, often x miles from the hold with ATC deciding which way to turn. It becomes quite difficult for ATC calculating when to bring the traffic on towards Heathrow, especially if the wind is strong. I saw an aircraft attempt to join the Bovingdon hold and he ended up almost at Ockham. I still have the grey hairs to prove it.

[philbky]

That's interesting re the moving the holds. In May 2012 I was travelling SNN-LHR on the 07.30 Aer Lingus flight. We were held on the ground at SNN for 50 minutes due to delays at LHR caused by strong crosswinds (bring back 23!). After a very slow descent compared to normal on that service we turned hard left, away from what I would have expected had we been taking the Ockham hold. I know the area west of LHR well both from on the ground and in the air. The day was extremely gusty with various levels of broken cloud and good visual reference points on the ground. We proceeded to hold in a right hand orbit with various aircraft above and below. There was another stack to the south of us which I took to be the Ockham hold. From sighting Reading railway station, White Waltham airfield and the position of the Thames, I took it that an additional hold had been set up based on Woodley.
We eventually exited to the south south east and joined a stream of aircraft ahead and behind from Ockham at approx 45 degrees, turning left into the stream to come around for an interesting cross wind approach and landing on 27R. The weather abated a little during the morning but we still had a 40 minute hold on the ground on departure to Houston that afternoon in wind which was sometimes gusting at 90 degrees side on to our BA 777, strong enough to rock the aircraft a little whilst waiting for push and enough to solicit an apology from the flight deck.

[wiggy]

does a 5 degree ILS scan cause problems in strong headwinds? I

What's that?

there was a strong crosswind and I it appeared that we came in at an angle of more than 5 degrees to the runway (although that may have been an optical illusion) or do pilots have to rely on a visual approach in such circumstances?

Ah....there's nothing scanning, in the radar sense..the ILS localiser defines an electronic centreline using a couple of fixed signals. The combination of those two signals is picked up by a very simple non-scanning VHF aerial on the aircraft and decoded by a magic box to give the pilots a left/right/ on centreline indication. It doesn't matter within very broad limits where aircraft is pointing, if you are physically somewhere near the centreline, even if flying through it at 90 degrees, or perhaps even flying away from the airport you'll still get the Left/Right/Centre indications on the Flight Instruments.

Moving to the case you describe, crosswind, yes the aircraft will be pointing off at an angle to the runway but you/or the autopilot still tries to fly (track) along the ILS/runway centreline. As an extreme example the likes of a 777 will autoland, using the ILS, with a crosswind of 40 knots - in that case the aircraft just tracks along the centreline, despite the nose pointing away from the runway by very roughly 20 degrees..(that said, you don't really want to actually touchdown with that amount of drift still applied, but that's a gear/tyre issue rather than a problem with the ILS).

BTW having operated into LHR for over 20 years the ATC pros here are coming up with a lot of "blimey, I didn't know that" stuff - thanks ladies/gents:ok:

[DaveReidUK]

BTW having operated into LHR for over 20 years the ATC pros hercoming up with a lot of "blimey, I didn't know that stuff" - thanks ladies/gentsWhich reminds me that we never heard back from the OP - has he been blinded by science or is he just plain ungrateful ? :ugh:

[treadigraph]

the holds are moved all over the place, often x miles from the hold with ATC deciding which way to turn

I happened to be looking at FR24 when the Ethiopian 787 got singed - I think there was another incident which closed 09R a short while earlier too; there seemed to be aircraft holding at locations all over the SE - and this before FR24 showed as many aeroplanes as it does now.

[HEATHROW DIRECTOR]

treadigraph... Exactly. When it "blows" the fancy book work doesn't cope so then the ATC people fix it themselves.