Runway alternation at LHR over the years

[DaveReidUK]

I'm researching the history of runway alternation at Heathrow over the years since the introduction of the 3pm westerly runway swap in 1972. While the basic concept has remained the same over the intervening years, there have been a number of tweaks, particularly as regards night and early morning flights.

Can anyone help with the dates and details of the various changes to the alternation scheme ?

So far I have identified:

1960s (year?): introduction of Westerly Preference
1972: introduction of daytime westerly alternation
1999: introduction of night time easterly/westerly alternation (wind-dependent, obviously)
2000: start of early morning (0600-0700) alternation trial
2009: introduction of permanent early morning alternation

So how, for example, were night flights alternated (if at all) pre-1999 ?

And how exactly does the current scheme work at night ? Alas, the BAA Heathrow website isn't much help - there's a rather confusing page which says:

"The present pattern provides for one runway to be used by landing aircraft from 06:00 until 15:00 and the other runway to be used from 15:00 until after the last departure (normally starting with the midnight hour), after which landing aircraft use the first runway again until 06:00." [my emphases]

That doesn't seem to correspond with what actually happens nowadays at night, or indeed with published landing runway alternation programme which implies that the designated 0600-1500 landing runway differs from the night time runway for 2 weeks out of every 4.

So is the BAA's description a reference to a previous, now superseded night alternation scheme, or is it simply wrong ? The fact that the same page refers to 0600-0700 alternation still being a trial, whereas it became permanent in 2009, could perhaps indicate that it's describing what happened several years ago and just hasn't been updated since.

[DaveReidUK]

So is the BAA's description a reference to a previous, now superseded night alternation scheme, or is it simply wrong ? The fact that the same page refers to 0600-0700 alternation still being a trial, whereas it became permanent in 2009, could perhaps indicate that it's describing what happened several years ago and just hasn't been updated since.

In the absence of any controllers who can remember the above, some more research has unearthed an explanation.

It's apparently a reference to a short-lived regime, introduced in December 1999, which extended daytime 27L/27R alternation to the night period (11pm to 6am).

This in turn was superseded by the introduction of the 2/4-week easterly/westerly alternation scheme, which removed Westerly Preference at night, implemented following the 2002/2003 runway resurfacing and continuing to the present day.

Mystery solved !

[BBK]

DRUK

I don't believe there was night alternation during the early 90s but I'm relying on my all too fallible memory!

rgds

BBK

ps I believe the night regs were revamped about 1993 and ran until late 90s?

[chevvron]

HD is never here when you need him.

[Sir George Cayley]

My recollection is that Alternation was a major part of the Cranford Agreement. Unfortunately it appears that no-one can find said parchment, so Heathrow (their new name) need to find their corporate cahoonas and introduce parallel mixed mode ops.

It would save having to dig up Sipson Rd, but hey you can't have everything.

SGC

[BBK]

Sir GC

Maybe no one can find the agreement because it was never written down in the first place!

I posed the same question many years ago to an official in what was then the Dept of Transport. He recounted a story where a minister went down to Heathrow when it was being developed as London's main airport so probably early to mid fifties. He, the minister, promised the local residents that Cranford would not have aircraft overflying it and this included landing as well as departures.

The point of the story was that it was not documented anywhere that this chap knew of within the DoT, as was, and so the 'Cranford agreement' became set in stone even if it was never formally written down. How true is all this? I have no idea but as you say it will be put under the spotlight. HACAN etc are formidable campaigners so it will not be an easy ride for 'Heathrow' although my money is still on a third runway and T6.;)

BBK

[DaveReidUK]

I posed the same question many years ago to an official in what was then the Dept of Transport. He recounted a story where a minister went down to Heathrow when it was being developed as London's main airport so probably early to mid fifties. He, the minister, promised the local residents that Cranford would not have aircraft overflying it and this included landing as well as departures.

That's interesting. I hadn't appreciated that the Cranford Agreement (July 1952) prohibited 27R landings as well as 09L takeoffs, but that would explain why 27L/27R alternation didn't start until 20 years later.

The point of the story was that it was not documented anywhere that this chap knew of within the DoT, as was, and so the 'Cranford agreement' became set in stone even if it was never formally written down. How true is all this? I have no idea but as you say it will be put under the spotlight. HACAN etc are formidable campaigners so it will not be an easy ride for 'Heathrow' although my money is still on a third runway and T6.

Actually, it would seem that the abolition of Cranford isn't being seen as particularly controversial by any of the campaign groups. On the contrary, there are protests at the moment about BAA dragging their feet on implementing the taxiway changes needed to allow post-Cranford alternation on easterlies.

[pax britanica]

Although I knew nothing of the Cranford agreement as a 13 year old spotter in mid 60s who live south of LHR I certainly knew that there were never any take offs from 28L and a lot of the landing aircraft turned off too early for me to see them well so that supports the views/comments that alternation came after the sixties. Of course back int he 60s there were a few other runways to choose from as well and I think a simialr arrnagement worked there in that 23L was used for landings but all take offs when that was the case were on 23R so perhaps way back someone had the idea of a clear preference for a 'take off runway and a landing runway from each of the the parallel pairs the airport originally had.

I think much of LHRs problems stem from usual Brit short termism in that LHR has clear physical boundaries Bath road/A30/Reservoirs plus fairly large villages immediately north and south. Howeevr a huge amount of the development North and South in terms of housing estantes and airport support facilites all took place from the mid 60s onwards. Both the Sipson /Harmondsworth areas to the north and Stanwell to the the south were really pretty tiny until then but no effort was made to preserve space for the future merely to get on and build builf build leaving LHR hemmed in.

I still think something has to be done at LHR because the other solutions leave west london without an airport. This is not going to work because the existance of LHR has meant that ina ddition to the 50 odd thousand airport workers a very large proportion of business pax all live west of london or west of LHR and hi speed rail links will onlydirectly link Central London to Boris island NOT the huge West london/ west of Heathrow catchment area.

[HEATHROW DIRECTOR]

Those with access to "Heathrow ATC - the first 50 years" can check page 49 for info on alternation. It started in 1972.

[DaveReidUK]

Those with access to "Heathrow ATC - the first 50 years" can check page 49 for info on alternation.

I have, and I did. :O

Excellent book, by the way, with masses of interesting facts and anecdotes. Highly recommended.