Heathrow Approach Path

[krsmith]

Heathrow landing paths and The Hare & Hounds

My question follows an earlier query on landing paths into Heathrow. This generated some informative replies – for which many thanks - but my thread was hijacked before I had a full answer. So I am trying again – and this time I have done some basic arithmetic and I am providing a navigation aid

I live in East Sheen 7.9 miles due East of Heathrow so I have had plenty of opportunities to observe planes landing on Heathrow South runway. And it is clear to me that landing aircraft approach Sheen over a corridor that I now estimate at half a mile. But when I first mentioned this this in a pub conversation I was told that I am mistaken and that all flights over Sheen are already aligned with the runway centreline .Later on, this line was taken by most respondents.

So let me outline what I see at street level and the quickest way is to Google Barnes Home Guard. Click on its neighbourhood map and look for the Barnes Home Guard, which marks the southern limit of the flight corridor, the Hare and Hounds, an excellent pub on the Upper Richmond Road, marks the centre line of the flight corridor, while Mortlake Station marks its northern limit. You can also use Webtrak, Heathrow Airport’s excellent animated web map, to track the flight paths to aircraft landing at both runways

For me, the most relevant replay to my initial query was provided by a Heathrow Controller who stated that, “all flights 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”. This fits with what I see. Sheen marks a transition point where all flights switch to their Instrument Landing System (ILS) on the final approach.

But this is not just a good-natured pub discussion. In Sheen, and elsewhere across West London, by rotating flight approach paths for individual runways those living beneath its flight path gain a welcome respite from aircraft noise. I speak from personal experience. So this leaves one last question. Am I still buying – at the Hare and Hounds, of course?

[DaveReidUK]

Sheen marks a transition point where all flights switch to their Instrument Landing System (ILS) on the final approach.No, it doesn't.

During the day, any flight that is not established on the ILS by 8nm from the threshold (roughly overhead Putney in the case of the southern runway) is automatically classed as a "late join" and reported as such in the airport statistics.

For 2012, late joins accounted for about 1% of arrivals. So even if all the offenders were flights coming in over Sheen, that would still mean that more than 97% were already established on the ILS well before they got to you.

[HEATHROW DIRECTOR]

Sheen has no significance in the Heathrow approach procedures. As I said earlier, all flights into Heathrow are radar controlled and the exact points at which flights join the ILS is determined by the radar controller and nothing else. The radar controllers position aircraft on to a "closing heading" such that the aircraft approaches the ILS beam at an angle. The aircraft then established on the beam and continues descent on the ILS towards the runway.

The runways, when landing on westerlies (towards the west) are swapped over at 3pm. Otherwise, one is for landing and the other for departure. This is strictly controlled and all traffic, from north and south, lands on the same runway. When the wind is from the east, the northern runway is for landing and the southern is for departure.

I worked as a Heathrow radar controller for 31 years so I am familiar with the system. However, since I retired some things have changed, e.g. we were not restricted to an 8nm final approach and would often put aircraft on the ILS much closer to the airport.

HTH

[krsmith]

I understood what you said the first time - that flights are folded into the ILS approach under ground control.And I appreciate your experience. So what should I conclude when when I watch a succesion of early morning planes flying precisely in line ahead over may house and a quarter of a mile from the ILS approach path?

[DaveReidUK]

So what should I conclude when when I watch a succesion of early morning planes flying precisely in line ahead over may house and a quarter of a mile from the ILS approach path?Can you give us an instance of when this has happened - date and time(s) ?

[HEATHROW DIRECTOR]

krs. I have absolutely no idea why aircraft should be a quarter of a mile from the ILS. I think you must have your measurements wrong. Long time ago I had the misfortune to have to show round a bunch of anti-noise freaks from Windsor. They swore that aircraft flew down Windsor High Street at 200 feet. I showed them the radar which indicated that aircraft were over a thousand feet above that. Do you think they believed me? Not a bit! They swore that I had fixed the radar!

[wiggy]

So what should I conclude when when I watch a succesion of early morning planes flying precisely in line ahead over may house and a quarter of a mile from the ILS

Just a thought - can I ask at what time of day precisely? I think that between 0600LT and 0700LT you can have traffic landing on both of the westerlies. I'm well aware that the lateral separation of the two localisers is more than a quarter of a mile but it may be one explanation for the apparent "spread".

As an frequent "end user" of the services provided by our esteemed colleagues in ATC :} I'd be very concerned and very very surprised if inbound to LHR I wasn't established on the assigned ILS localiser by 8 miles...

[TopBunk]

As (a now retired) very frequent user of LHR's excellent ATC services, I can concur in what has been written above by DR, HD & Wiggy.

An aircraft flown on autopilot will very accurately track the extended centreline of the runway and not show any significant degree of divergence from it.

Remember though the winds aloft can vary very significantly, from aa 50kt southerly through calm through a 50kt northerly. This will result in the aircraft tracking the centreline but with a heading variation of about +/- 15 degrees from that track.

I wonder if it is you being visually deceived by wind effects?

Another thought .... for you to see the aircraft 8 miles out when they are at 2500ft or so, the weather/cloud base is obviously quite high. Maybe a pilot hand flying the aircraft has slightly diverged from the centreline, although a +/- 300 metre deviation is quite large.

I prefer my first theory on balance.

[DaveReidUK]

I think that between 0600LT and 0700LT you can have traffic landing on both of the westerlies.I wondered about that too - you are correct in that it happens pretty well any day that 27s are in use (it's referred to as TEAM - Tactically Enhanced Arrival Measures).

But it doesn't really fit with the OP's observation of:

a succession of early morning planes flying precisely in line aheadPresumably if it had been TEAM he was watching, he would have seen aircraft on both ILSs simultaneously from his location.

I still think the best way to solve the conundrum will be if he gives us dates and times so we can all look at WebTrak for the period in question and see what the radar-derived tracks say.

That should satisfy all parties, unless of course NATS are part of the conspiracy too. :O

[chevvron]

Oi HD, why do Heathrow arrivals use Craven Cottage as turning point; it's most distracting when Fulham are playing Man U.

[HEATHROW DIRECTOR]

Ssssh T... don't give away trade secrets!

[krsmith]

Heathrow Approach and The Hare & Hounds
Hi Guys
I just happened to step out of the door moments after reading the latest contribution to this thread and there flying immediately overhead – and passing the Barnes Home Guard – was a TWA flight in scarlet and looking magnificent in the autumn sun.
I have been asked to provide some examples of flights so as I walked I made some quick notes on a scrap of paper – you will have to forgive some possible errors as I can’t read my writing in full. However there is enough here for you to check the details when Webtrak comes out in 24-hours’ time.
To make sense of what you see just use the Barnes Home Guard or Hare & Hounds web sites. I have been so disappointed that no one has yet bothered to use it.
I have a few comments to make but will reserve these for later.
Friday 15 November 2013
Time Flight Where Seen
13.48 TWA Directly over Barnes Home Guard
13.50 BA? Shifting north towards Shrewsbury Avenue
13.53 Between Shrewsbury Avenue & Upper Richmond R
13.50 Small jet overflying Muirdown
13.56 Possibly private jet just south of Upper Richmond Road
13.58 Private jet just south of Upper Richmond Road
14.00 Virgin Exactly Tracking Upper Richmond Road & overflying Café Nero
14.00 – 14.20 Good coffee
14.20 -14.45 Now off-duty but I observe a flock of jets in quick succession tracking the Upper Richmond Road and effectively on Runway Two axis

[chevvron]

If you stand at the north end of Putney Bridge the Heathrow 27L arrivals go straight over you and along Upper Richmond Road, which make them clearly visible when seated in the Hammersmith Stand at the Cottage; if they're landing 27R ie before 3 pm, you don't see them when seated as they're just that little bit further north.

[FLCH]

Teeny Weenie went bust years ago, it must have been some other carrier.

[HEATHROW DIRECTOR]

He probably doesn't understand.... TWA doesn't operate any more.

<<Runway Two axis>>

Runway Two? Where's that?

This thread is going the same way as one earlier in the year. Experts did all they could to answer questions but the originator either wouldn't listen or did not believe them. I think it's time to give up....

[oceancrosser]

Bartender! I will have what Mr.Smith is having! Maybe I will get to see Pan Am and BOAC, and a Concorde...

[treadigraph]

and a Concorde...

Nonsense! Bring on the Connies and Stratocuisers....

[DaveReidUK]

To make sense of what you see just use the Barnes Home Guard or Hare & Hounds web sites. I have been so disappointed that no one has yet bothered to use it.

WTF is that supposed to mean ?

Is this just a wind-up after all ?

[krsmith]

An audio check on early morning flights
Once again I must commend oooooone respondent for suggesting that I provide evidence to back up my claims. So as I watched PBS’s excellent series on JFK Kennedy this morning at 7am this Saturday morning I realised that Heathrow’s southern runway was particularly busy and so I jotted down the time as each passed overhead. Of course these are audio observations - I certainly was not going to the window every two minutes for a visual check.
Between 07.13 and 08.00 I noted 14 flights roughly every two minutes. There were flypasts at 13,15,17,27,34,35,37,40,45,47,50,52,54,55,57 past 07hrs. And when eventually I glanced out of the window at 8.15, a BA Flight passed directly overhead. It was immediately followed by a second BA flight, then an unidentifiable flight at 8.18 and at 8.19 a flight with a green tail fin. All of these flights were on the southern edge of the Heathrow South landing corridorcorridor this close to Heathrow is wider than you think?
Apparently not Heathrow director has a closed mind

[HEATHROW DIRECTOR]

Just about the most accurate track an aircraft will fly will be when it is on the ILS approaching the runway. The ILS systems at Heathrow are extremely accurate and having worked with them for so long I know that to be the case. The majority of aircraft arriving at Heathrow will be on autopilot on the approach and some will carry out fully automatic landings. Such operations are conducted with extreme accuracy.

[wiggy]

If you're claiming all these flights this am were to the south of the "Heathrow south landing corridor" whatever that, is, has it crossed your mind that maybe the corridor isn't where you think it is?

BTW shame you got up so late, you missed logging my arrival...........which was established on the centreline of 27 left at over 10 miles out.....

[HEATHROW DIRECTOR]

Thanks Wiggy... but I think we're up against a brick wall!

[TopBunk]

Well I have just wasted abou 16 minutes of my time looking at the webtrak data for Friday at the times the deranged bloke mentions.

Surprise, surprise, all the flights followed the same ground track between 1346 and 1402!

From my research. the flight sequence was:

~1346 CZ303 from CAN B788
~1348 JJ8088 from GIG B76W
~1350 BA847 from WAW A320
~1351 BA549 from FCO A320
~1352 KL1019 from AMS F70 (one of his private jets perhaps?)
~1353 SK805 from OSL B73G
~1355 VS401 from DXB A333
~1357 BA541 from BLQ A319
~1359 LH908 from FRA B733
~1400 BA18 from ICN B772
~1402 BA1311 from ABZ A320

Now will you please either review the above and come back and admit you are wrong, or just take your trolling elsewhere and keep on smoking your wacky baccy:ugh

[Crazy Voyager]

Sorry can somebody remind me, what is the actual question here? If the aircraft flying over this pub are all aligned with the ILS or not?

[118.70]

I had a go replaying webtrak for much of Friday's period that you mentioned. I could not identify your TWA flight that went over Barnes Home Guard. On the magnification of the map that I used (Zoom Level 6) the majority of flights passed about 1 character width below the C of Church Avenue (the only named street running North-South ish on your axis of Barnes Home Guard to Mortlake Station). Occasionally the track might pass through the C of Church Avenue or where I guessed 3 characters south of the C would be.

However, there were a couple of flights where I would agree the planes were not established on the ILS when crossing this axis - but nowhere near as far off as a direct overhead flight over Barnes Home Guard.

AF1780 13:41 (crossed URR at East Sheen Ave)

LH908 13:59 (crossed URR at Richmond Park Road)

The private jet (coloured blue on Webtrak) was visible at 13:51 but is touching the end of Milton Road rather than overflying Muirwood Avenue and is essentially flying the same track as the majority of planes.

[118.70]

http://www.heathrowairport.com/static/Heathrow_Noise/Downloads/PDF/LHR-FEUQ22013-FINAL.pdf

(page 17) gives recent monthly figures for the percentage of "day joining point lates" and is under the 1% figure as Dave Reid mentions.

On an unrelated matter, I'd be interested in any explanations for the high percentages of flights taking off from 09L that don't manage to keep to track (09LCPT, 09LMID, 09LSAM) - page 10 of the above report. Numbers of flights from 09L aren't large (yet !) but those figures are very low.

[HEATHROW DIRECTOR]

So is 09L used regularly for departures now?

[118.70]

Planning permission for the full works to do the resurfacing next summer is still awaited, but the report for Jan-Jun 2013 said :

"As the [southern] runway resurfacing continues, we
hope to get some meaningful data for departures off 09L to
look for trends and ways of improving performance. So far this
year, ANOMS has recorded 907 departures off 09L.

[PAXboy]

Suggestion krsmith:


A modern laptop with some speed and some Wi-Fi
Tune it to a popular site of the net where the numbers 24 are preceeded flight and radar ;) This will provide real time id of all a/c and details
A thick overcoat and scarf
A mug of tea/beer
A reclining chair in your garden
Make notes
Report! :}

[118.70]

PAXboy,

Can you tell me why some flights on flightradar24 are shown in incorrect positions ?

For instance, I had a glance at the same period of activity as the orignal poster (Friday 15th November 13:30 ish) and most of the tracks were on the same alignment as Webtrak.

However KLM1019 at 13:53 was shown as considerably to the north of the glidepath , even passing to the north of Mortlake Station (the northern marker mentioned previously !), overflying the Mortlake Brewery and just skirting the bottom of the bend in the Thames. I guess the displayed track was about 400m from the actual. Presumably the plane didn't touch down on the Terminal 3 stand where it ends up on FR24 or we would have heard about it !!

[DaveReidUK]

Can you tell me why some flights on flightradar24 are shown in incorrect positions ?The answer relates to how aircraft derive the positional data that they transmit, which in turn is picked up by enthusiast feeders and forwarded to FlightRadar24.

Most modern commercial airliners have GPS integrated with their avionics. Those are the ones that are displayed tracking straight down the ILS.

Some older aircraft, although they make equally accurate approaches on the ILS, don't have an integrated GPS. The positional data that they transmit comes from inertial-based systems that are subject to inaccuracy and drift.

While that doesn't affect the operation of the aircraft (or of ATC, come to that), it does mean that the aircraft appear to be in the wrong place in the plan view that FlightRadar24 provides based on the dodgy data.

WebTrak, on the other hand, is powered by data from NATS radars and so doesn't suffer from this problem.

The older aircraft I referred to above include 737 Classics, early examples of the A320, 767 and 777, and aircraft such as the KLM Fokker 70 that you observed.

[Trinity 09L]

krs
No complaints from directly under 09L, but wait we will get relief when 09R is in use and 09L for departures - enjoy, btw has your property depreciated? :uhoh:

[krsmith]

Thank you Heathrow for your prompt reply. May I just say once more the accuracy of ILS systems was never the issue with me. I have no doubt that it can bring pilots home safely in ground zero fog.

And I might add that I have solved this puzzle to my satisfaction. Yeserday morning at around 7.30 I noted the time of 14 flights overflying my house. Today I visited Webtrack to check on these fleets and - just as I expected anmd one respondent pointed out - Heathrow was running both runways in parallel throughout this period - and indeed most of the morning.

As I live one quarter of a mile south of the ILS axis as I have pointed out on several occasions - so the only logical explanation is that the planes I hear - and see overhead - have not yet switched to ILS. And indeed you youself said that Heathrow controllers make the decision to hand over to ILS according to operational requirements.

I also realise that it was unwise to ask you guys - pilots and controllers - to verify what is happening at street level. You see the world through cockpit instrument panels and radar screens. Asking you to navigate by street names and pubs was a bit much.

[DaveReidUK]

so the only logical explanation is that the planes I hear - and see overhead - have not yet switched to ILSYes, as per the previously quoted statistics, you can expect up to 1% of arriving flights over your head to fit that criterion.

[diginagain]

Asking you to navigate by street names and pubs was a bit much. You think? :)

[HEATHROW DIRECTOR]

No, they use the AA Road Atlas..

[DaveReidUK]

On an unrelated matter, I'd be interested in any explanations for the high percentages of flights taking off from 09L that don't manage to keep to track (09LCPT, 09LMID, 09LSAM)There was a reference to this in the previous thread started by the OP:

http://www.pprune.org/spectators-balcony-spotters-corner/525519-heathrow-approach-path.html

Because the westbound standard instrument departure routes (SIDs) from both 09L and 09R involve a right-hand turn, there is a potential conflict between departing aircraft (shown in green on the graphic) and arriving flights (red) coming off the Biggin and Ockham holding stacks and being vectored for an approach from the west.

http://www.google.co.uk/url?sa=i&source=images&cd=&docid=L2UjuwgiXeJYHM&tbnid=TYUY9eM1gpY10M:&ved=0CAUQjBwwAA&url=http%3A%2F%2Fyour.heathrow.com%2Fwp-content%2Fuploads%2FEasterlies-YourHeathrow.jpg&ei=GNaJUpLLBdKv7AayiYDAAQ&psig=AFQjCNGwLLTjVwky0aFzUaZpX1T6qkmEOg&ust=1384851352176943

The controllers' priority is to keep those aircraft safely apart, if necessary by directing them away from the SID.

[Gonzo]

The CPT is the only 09 departure that requires deviation from the SID for separation purposes against inbounds.

The MID and SAM departures are separated. However, all departures once above 4000ft can be taken off-route.

[DaveReidUK]

The MID and SAM departures are separated. However, all departures once above 4000ft can be taken off-route.I'm guessing that the confusion arises from the report linked in post #26, which shows very low on-track percentages for 09LMID and 09LSAM departures from March to June of this year (during the southern runway resurfacing programme).

That's out of around 900 departures in total on 09L during the period, so we're talking about more than just a handful of flights being off-track for whatever reason.

[118.70]

09LMID 33.3% on track could be 2 out of 3 off track

09LSAM 6.7% on track is at least 14 out of 15 off track

Is there something that is limiting operation of the SID ?

[DaveReidUK]

09LMID 33.3% on track could be 2 out of 3 off track

09LSAM 6.7% on track is at least 14 out of 15 off track

Is there something that is limiting operation of the SID ?If it helps, the monthly breakdown of 09L departures this year is as follows:

Jan: 18
Feb: 8
Mar: 239
Apr: 236
May: 204
Jun: 217

I don't have the breakdown by SID, and that varies from day to day anyway depending on NAT tracks, en route winds, etc, but I've seen figures (I don't know how representative they are) showing around 6% of departures each on CPT and SAM, and around 17% on MID, with the remainder on DVR, BPK and BUZAD/WOBUN.

[PAXboy]

krsmith The post #2906 in thread: http://www.pprune.org/airlines-airports-routes/200585-heathrow-146.html should interest you. at the time of writing, the last post in the thread.

[krsmith]

Thanks for the pointer to your thread. Noise was not theimmediate reason why I started my thread on approach paths, but naturally, every one living in West London is interested in the subject.

[DaveReidUK]

Thanks for the pointer to your thread. Noise was not theimmediate reason why I started my thread on approach paths, but naturally, every one living in West London is interested in the subject.I would imagine that the point Paxboy was making (and if he wasn't, I will) is that the chart shows an entire day's worth of arrivals (in red, around 650 of them in total, roughly 50% on each runway), and of those, only a handful join the ILS after Putney (as the aforementioned statistics confirm).

[PAXboy]

Thanks DRUK, that was the thought. That multi-overlayed image seems to answer the o/p question with (what the vernacular refer to as) a 'Slam-Dunk' ;)

[DaveReidUK]

Thanks for the confirmation. I look forward to the OP moving the goalposts yet again, in an effort to prove that the statistics are d*mn*d lies.

[HEATHROW DIRECTOR]

<<every one living in West London is interested in the subject.>>

How many of those have moved in since the airfield opened?

[PAXboy]

It would be interesting to try find long term residents who can (accurately) remember the progression from (examples only):


Constellations and other large 4x piston
707 / VC 10
747-100
A340 / 747-400
A380
777 / 787

Also


DC-9 / BAC 1-11 / 737-200
727 / Trident / L-1011
767 / A310
737-400 / A320


The factors should be for both noise AND smoke! Today might not be ideal but BOY things have changed in 50 years.

But then, that would be a good news story and no one wants that. Particularly the HACANites. (No, I don't deny their right to do the best for their subscribers, that is what every organisation does)

[HEATHROW DIRECTOR]

Perhaps a few Coronados and BAC-1-11s down the approach would remind those people how lucky they are.

[Trinity 09L]

Staines 1972 - 1996, Windsor '96 to present, lets not forget the Convair 880, all the Russian jets & props- what noise :rolleyes:

[HEATHROW DIRECTOR]

Yes indeed - fantastic. My family used to live under one of the approaches to Brize Norton when they were doing crew training with VC10s. What joy.

[mixture]

Perhaps a few Coronados and BAC-1-11s down the approach would remind those people how lucky they are.

Or just Concorde into LHR. :E

[ExRAFRadar]

I live in Twickers and when you lot are on Westerlies going into Heathrow I get a fantastic view of the 'String of Pearls' as they all line up nicely. And that mus be at least 5 miles from my back window.

Going into Waterloo in the morning's I don't see many aircraft that are not obviously on ILS until we get to about Vauxhall . The you start to see a few turning gently to intercept the ILS. Matter of fact when I took my daughter into London a few months ago I managed to persuade her I was bit psychic as we would look at an aircraft and I would say 'She's going to turn left anytime now' and then she would.

As for the noise. Well I have lived here for 9 years now, 8 of those in Whitton where some of the flights flew right overhead. The new, modern jets have much reduced noise footprint. Those old 747's would rattle the windows sometimes.

My only complaint is that the old Queens building has gone. Many happy hours up there as a kid with that bloody big book 'Spotters list of Aircraft' (or whatever it was called),

I might pop down the Hare and Hounds and see what all the fuss is about.

[118.70]

How late can you get established for landing ?

I was intrigued by the approach of BA212 early on Saturday morning

WebTrak: Heathrow (http://webtrak.bksv.com/lhr)

at approx 04:48.

It appeared to meander following the curves of the Thames, got almost in line for the wrong runway over Mortlake and then turned off to get in line for the northern runway just about as it crossed the Piccadilly line at Hounslow.

I guess it isn't a plan to spread the early morning 747 noise around a bit !

[TopBunk]

How late can you get established for landing ?

I took a look at the replay and it is a little unusual - could have initially been a late turn on by ATC to the localiser, causing an overshoot and reposition from the south, but then it veered off again - as I say, a little unusual.

In terms of how late can you etc, well at JFK when doing the Carnasie to 13L then typically you don't roll wings level until about 300 ft (or 1 mile) from the runway vs the 1400ft / 4 miles in this case. The old Kai Tak IGS approach to 13 was similar with a ~50 degree to the right started at 600 feet / 2 miles.

[HEATHROW DIRECTOR]

I think there's more to that flight than meets the eye. In my book, QF9 off LAM should have been ahead of BA212 which seems to have had priority - high speed, southerly heading off BNN then a left turn downwind inside the QANTAS. Speed on base leg was high, leading to going through the LOC. Possibly a medical emergency?

[Hartington]

Prior to 9/11 I happened upon a BA Captain I know on a flight from CDG to LHR and was invited to the cockpit. As we turned finals there was a Virgin 340 with an emergency crossing our track. We were heading for 27R he for 27L (coming from the north - right to left across our track). He turned on towards 27L but then continued the turn to line up on 27R ahead of us. The plane lined up on 27L had failed to depart because he'd seen something falling from the preceeding departure onto the runway. Sounds very similar to BA212.

We ended up getting clearance to land as we crossed the perimiter track (or that's what it felt like) and overheated the brakes in clearing the runway in time for the next plane behind us.

Colleagues in the cheap seats had no idea until I told them!

[Hartington]

And, on the subject of people living under the approach path. I was born in Chiswick and for the first 5 years of my life lived right under the 28R centre line. Then we moved 200 yards nearer to Heathrow so we were still under the 28R centre line. My parents moved out in 1977 some 28 years later.

We went from everything being piston/prop via what I might call the "Viscount/Vanguard" era to the Comet, 707, BAC111, 727 and early 747s. It wasn't just the aircraft that were different, it was also the way the approach was flown - gear and flaps deployed earlier than they are today so everyone on high power. In the early days GCA then ILS both captured from below so often lower than today.

It's not as if you could hide the planes but when my parents put the house up for sale they had no problem finding a buyer.

As for the accuracy of the approach path I wasn't measuring but even in those days the vast majority seemed to pass right over the house. There was very little deviation.

[PAXboy]

I unexpectedly encountered a reference to the man who developed a means of measuring the annoyance caused by aircraft to people living near Heathrow airport, taking account of how close they were to the flight paths and numbers of the aircraft coming in.

The construction of the Noise and Number Index (NNI) was a major innovation. It demonstrated the strength of the link between how annoyed people were and the physical measurement of the noise that they were experiencing.

The development of such an index influenced the subsequent design of aircraft, the noise restrictions placed on them and the orientation of runways. The study also helped make the case for compensation to be paid to the families living at the most severe NNI levels.

The work led to an invitation to him from the Port Authority of New York to work on the local community’s response to Concorde. He accepted but concluded that the noise annoyance evidence against Concorde was not strong enough to justifying banning it.

[DaveReidUK]

And, coincidentally, NNI celebrates its 50th birthday this year, although for practical use it was replaced 20-odd years ago by Leq.

1963 | 1254 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1963/1963%20-%201254.html)