The Trials of Heathrow – “Operational Freedoms”, “Respite” – layman’s guide to what’s going on and what it means

The Operational Freedoms trials at Heathrow have been going for the past year, and are due to end at the end of February. The reports about the trials are somewhat baffling documents to the non-expert, and some clarity is needed.  There are also some trials taking place at present on flight paths at night, in east and south east London, to see if residents can be given some respite periods.  These are both quite separate from the threat of both Heathrow runways being used, all day, for both landings at take-offs at the same time (called mixed-mode, in contrast to the current system, called runway alternation).  John Stewart has done a short briefing on the trials, to help everyone understand the basics of what is going on.


                                                                   BAA map showing aircraft flight paths over west London in August 2012

The Trials of Heathrow

Explaining the differences between mixed-mode, operational freedom trials,  runway alternation at night and respite periods.

The ‘Operational Freedoms’ trials finish at the end of February.  They are not to be confused with the dreaded ‘mixed-mode’.  They don’t happen during the night.  And they are certainly quite different from the ‘respite’ trials.

Confused?  Let me try to explain.  First, let’s start with understanding mixed-mode:


At present planes landing over London switch runways at 3pm to allow people in West London a half day’s break from the noise.  It is called ‘runway alternation’ and has been in place since the 1970s.  Mixed-mode would mean that planes would not switch runways.  They would land on both runways throughout the day.  It wouldn’t mean a doubling in the number of planes using the airport because it is simply too difficult and dangerous for planes to land on (and take off from) both runways every 90 seconds throughout the day.  But annual flight numbers would go up from 480,000, the current cap, to over 560,000 (about a 17% increase).  A truly dreadful prospect for residents many of whom only moved into West London because they knew they got a half day’s break from the noise.

A number of bodies, such as London First, back mixed-mode seeing it as a quick way to increase capacity at the airport.  However, NATS (National Air Traffic Control) have made it clear that it would take some years to rearrange the flight paths to allow mixed-mode to operate safely.  For this reason – and because they understand how deeply unpopular it would be with local residents – Heathrow Airport has recently dropped its support for mixed-mode.  A Heathrow source told the Times (4/2/13) “It would be a lot of pain for not much gain.”  So mixed-mode is not entirely off the agenda but, without the backing of Heathrow Airport, it is difficult to see how it could go ahead. [More on mixed-mode ]

Heathrow has been carrying out ‘Operational Freedom’ trials over the past year or more.   The aim has been to see if Heathrow can work more efficiently, without more aircraft movements.

‘Operational Freedom’ Trials

These are trials that are currently being carried out by Heathrow Airport and NATS.   The effect sometimes seems similar to mixed-mode but it is actually quite different.  For three months over Christmas 2011 Heathrow Airport was given permission by the Department for Transport to land planes on the ‘wrong’ runway, i.e. out of alternation, to try and prevent delays building up.  But there was one crucial difference with mixed-mode: there was no increase in the overall number of planes landing during the day.  Perhaps because it was winter, the number of complaints was not high.  A lot of people seemed not to notice there were a few more planes on the wrong runway. (There had always been some planes landing on the wrong runway when emergencies and other incidents arose).

The trials started again in July 2012 and will continue until the end of February 2013.  They are slightly different from the first trial.  Heathrow Airport is being allowed to land more planes on the wrong runway, in order to reduce delays.  And, this time round, it is being permitted to allow take-off planes to veer off their designated routes early in order to speed up operations.

Heathrow Airport has now  reported on the first four months of the trial (1 July 2012 to 27 October 2012.):   Phase 2 report   

It shows than an average of 27 planes a day landed on the wrong runway (out of a total of 650 arrivals per day).  Before the trials an average of 15 planes landed on the wrong runway.  The report also shows that about 6.5% of take-offs were allowed to leave their designated route early but on two routes the average was much higher at 28% and 39% respectively.  When planes are allowed to veer off early it can mean that people are getting planes overhead for the first time, certainly in any significant numbers.  Understandably, the complaints from these areas were high.

After the trials have ended at the end of February, Heathrow Airport, overseen by independent consultants, will assess and analyse the trials.  The figures will go to the Department for Transport.  If the Government wants to make the trials in one form or another, it will need to put the proposals out to public consultation.

How did the ‘Operational Freedoms’ trials affect night flights?

Night Flights

The operational freedom trials did not take place at night (11.30pm – 6am) nor during the hours between 6 and 7am when a lot of planes have always been allowed to land on both runways at the same time – with no runway alternation.  During the night (11.30pm – 6am) a different system of alternation operates.  Wind direction permitting, planes are meant to alternate the runway they use every week.  In a perfect situation planes would only land over a particular community one week in four.  That is not always possible because of the wind but no community in West London or Berkshire should be overflown more than every second week.  There are no take-offs scheduled between 11.30pm and 6am.

So what are the new Respite Trials, where are they taking place and when?

Respite Trials

For many years people in south, south east and east London have been calling for periods when they can be guaranteed some respite from the noise (day and night), similar to the runway alternation enjoyed by residents in West London.  After many years of pressure from HACAN, both the Government and the airport authorities now support the concept of respite periods.

HeathrowAirport agreed to trial a respite period for night flights before 6am.  This started on 5th November 2012.  It involves quite a complex series of no fly boxes and only applies to some areas in south, south-east and east London.  The theory is that every second week residents within or close to some boxes should get no flights until very nearly 6am, while the flights are routed over other boxes. This is reversed each week.  The trial is being monitored to assess how it is working.  The results, so far, are mixed.  The trial ends at the end of March when the results will be assessed.

John Stewart, HACAN

February 2013

 The trials of Heathrow   (Word document)



There is also a  short briefing, from HACAN, on Mixed Mode. (4 pages)

Mixed-mode Pamphlet Feb 2013


The Heathrow Airport webpage on Operational Freedoms Trials



Heathrow publishes its report on Phase 2 of its Operational Freedoms Trial

Date added: February 8, 2013

The Heathrow Operational Freedoms Trials will end on 28 th February, a month earlier than planned, as enough data has been gathered. The first report on the trials was produced in April 2012. Now the second report has been published, for the period July to October 2012. It is a complicated and technical document, that is not particularly accessible to the non-expert! However, in its conclusions it says that during the trial there were (on westerly operations) about 22 extra flights on the other runway, which would not normally happen, taking the number from an average of 15 to 37 per day, as this could be done if there was a 10 minute delay trigger. They also say there was a very tiny reduction in stacking time and thus fuel burned, though this may also be due to other factors. They also say the number of complaints was significantly up, that about 80% of the enquiries were accounted for by 10% of the callers, and about 60% of the callers made contact only once.

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Noise problems for some south east London residents from night noise trial

Date added: February 7, 2013

Heathrow Airport is currently running a trial, to see whether giving residents in one block of airspace in south east London, between 11.30pm and 6am, for some weeks, makes a difference. The trial is intended to give respite from night flights to one area for a week, with the planes then being directed over that area for another week. So people get a week off from the night disturbance. However, some of planes have been flying a route between the blocks of airspace, so residents there have been suffering more night noise than usual, while others have had less. There have been many complaints from Brockley, an area between Lewisham and Greenwich, and Assembly Member Darren Johnson has taken an interest in the issue. This trial ends in March. This is a quite different trial to the Operational Freedoms trials at Heathrow, looking into use of a different runway in order to reduce delays when there are specific problems. The Operational Freedoms trials are ending a month earlier than intended, on 28th February.

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