HACAN gets more questions about flight paths than about anything else. Where flight paths are, if flight paths change, are all-important to people.
Explanation of flight paths
Planes at Heathrow generally land and take off into the wind. There is one exception to this at Heathrow. When there is a light wind easterly wind blowing (less than 5 knots), operations continue as if a west wind was still blowing.
But note: the critical thing in determining the direction the planes take is the direction of the wind at 3,000 ft (which might not be the same as on the ground). See this presentation from the Met Office http://www.heathrow.com/file_source/HeathrowNoise/Static/HCNF_Met_Office_Presentation.pdf
There are sites where you can track the planes. But beware! Some of them are not too accurate. The best is Heathrow’s own site, Webtrak, http://www.heathrow.com/noise/what-you-can-do/track-flights-on-maps. There is a 20 minute lag but is nearly 100% accurate.
You can find maps of flight paths on Heathrow’s website: http://www.heathrow.com/noise/facts,-stats-and-reports/operational-data/annual-flight-maps
You can track flights as they land and take-off: http://webtrak5.bksv.com/lhr4
And you can see what the flight pattern was like over your house during the past six years: http://xplane.bksv.com/xplane/
When planes arrive at Heathrow they are held in holding stacks.
There are four of these:
- one over the Epsom area
- one over the Biggin Hill area
- one over the Epping area
- one over the Chesham area
A plane circles round in a stack until it is given the green light by the air traffic controllers to make its way to Heathrow.
It is then guided on to its final approach path which it joins anything between about 15 – 25 miles from the airport.
It will either land on the north or south runway. Planes only usually land on both runways between 6am and 7am (the busiest hour of the day).
Runway Alternation: One week planes coming over West London will land on the northern runway until 3pm and then switch to the southern runway. The next week it will be the other way round.
This is to give people living in the boroughs closest to Heathrow a half day’s break from the noise. People living between Heathrow and about Putney and Fulham benefit from this switch.
Sometimes, if delays are building up, Heathrow will land planes on the ‘wrong’ runway.
Cranford Agreement: At the moment, when the wind is blowing from the east and planes are landing over Berkshire, no switch takes place and all planes land on the northern runway over Windsor. But this is expected to end when something known as the Cranford Agreement will be terminated. The Cranford Agreement, which came into force over 60 years ago, prevented flights taking off from the northern runway over Cranford (in Hounslow). It meant all the planes had to take off from the southern runway over Hatton Cross, with them all landing on the northern runway over Windsor. It ruled out alternation from the west.
In 2009 the Government got rid of the Cranford Agreement but delays caused by the planning authority, Hillingdon Council, meant it took some years for it to complete all the planning hurdles. Now Heathrow says it intends to incorporate the taxiway work needed to allow planes to take off from the northerly runway into it wider construction works for a third runway. If the third runway is given the go-ahead, it means planes will not take off from the northern runway until the new runway opens (expected in 2025)
In a typical year, the east wind blows just under 30% of the time.
So, if you are relatively close to the airport the flight path situation is pretty clear and these flight paths have been in place since the 1960s.
It’s when you get further from the airport, that things get more complex.
The big change took place in the mid-1990s. Before that, most planes joined their final approach path round about the Putney/Barnes area (if they were landing over West London).
From the mid-1990s aircraft were expected to join their final approach path up to 25 miles from the airport (around the Lewisham area).
In order to do this, aircraft were guided from the stacks in a trombone pattern rather than taking a more direct route towards Barnes.
This ‘trombone’ method resulted in many areas, particularly in North, East and South-East London, getting many more planes than before. When the east wind blows areas west of the airport are similarly affected. (diagram by Heathrow Airport)
Since then there has been no fundamental change in landing flight paths but the way flight have been brought into land have changed. Many more planes are joining their final approach further out and there is evidence that the corridors the planes use (before they reach the final 15 miles or so) have become narrower: see http://hacan.org.uk/wp-content/uploads/2018/04/Corridors-of-Concentration-Report.pdf for details
Additionally, air traffic controllers make incremental changes which can mean an increase in flights over particular communities. The controllers are permitted to do this. These changes are not always permanent.
Are any changes in the offing? A third runway would mean changes. These are not discussed here as it is unclear what they would be.
Except in one important way, the departures routes have not changed since the 1960s.
Departures follow what are known as Noise Preferential Routes (NPRs). These are bands 3 kilometres wide.
The important change that has taken place in recent years in that new technology enables most aircraft to fly along the centre-line of the NPRs. This has resulted in concentration of planes over particular communities. It has been made worse for these communities by the fact that large, heavily-laden planes are flying lower after take-off than planes previously were. The CAA is currently undertaking a major study looking at the consequence of planes taking off more steeply. It is expected to be published in summer 2018.
HACAN would like to see more sharing out of the noise within the NPRs
Aircraft are allowed to leave the NPRs once they reach 4,000ft.
More Recent Trials
In 2011/12 and in 2014 Heathrow and the air traffic controllers trialled new take-off procedures. This resulted in some areas getting many more planes than they used to and some areas getting planes for the first time.
This caused much controversy. Although the trials have now ended, some people argue that things have not gone back to the way they were. Independent study were commissioned by Heathrow to assess the 2014 trials . These studies involved local community representatives from the areas affected who drew up the brief for the studies, appointed the consultants and oversaw the work.
The studies found that, with the exception of a change which air traffic controllers (NATS) made to one of the take-off routes, flight paths have gone back to the way there were: http://www.heathrow.com/noise/heathrow-community-noise-forum/flight-analysis
Future Flight Paths
Whether Heathrow gets a third runway or remains a two-runway airport, it will see the biggest change in flight paths since it opened.
This is being driven by new technology which allows planes to be guided more precisely. It is called Performance Based Technology (PBN). PBN will mean narrower, more concentrated flight paths.
In its 2017 consultation Heathrow asked for views on whether, when it designs its new flight paths, it should aim to a. affect as few people as possible (by concentrating all the flights over certain communities) b. to affect as few new areas as possible (by concentrating flights over existing areas which get them) or c. to provide as much respite as possible (by creating a number of PBN flight paths and rotating them).
It was not a referendum but Heathrow will be guided by the views expressed at its next stage when it draws up noise envelopes (the areas which might be impacted by flight paths). It will consult on these in 2019.
Around 2021 it is expected to consult on the detailed flight paths.
HACAN favours respite as the fairest and most equitable solution.
Heathrow published its long-awaited respite report commissioned from Anderson Acoustics on 16th February 2018. It is the first of its kind to be done. HACAN was part of the steering group. Summary video: https://youtu.be/7Z5mt7rKJgA . Where to find the reports: https://www.heathrow.com/noise/making-heathrow-quieter/respite-research