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Compton procedural change

March 2015

Heathrow secures NATS agreement to improve communications about operational changes to air traffic control

Following a change made by NATS last year to the way aircraft are directed within the airspace southwest of the airport, NATS has agreed to Heathrow’s request to urgently review the way they share information with the airport about changes which may alter the pattern of aircraft over communities living around Heathrow.

On 27 June 2014 NATS made a procedural change affecting the Compton route, one of the six departure routes used at Heathrow during periods of easterly winds. Heathrow was unaware of this change. The Compton route, is used by 16% of departing aircraft turning west when the airport is on easterly operations, equating to around 6% of total departures. Other departure routes are not affected.

Prior to the change, aircraft using this departure route were directed across a wide swathe of airspace before moving into the next sector of airspace anywhere within a 13-mile “gateway” near Compton (hence its name) at approximately 8,000ft. Since NATS made the procedural change, this gateway for departures has been narrowed to around 7 miles which means that aircraft are now climbing through a narrower area of the existing airspace in order to be in the correct location to go through the gateway. This has resulted in more concentration of departure aircraft activity over some areas and a reduction in others. It has also altered the position of some flights before they reach 7,000 feet, but not below 4,000 feet.

Areas affected by this concentration include Virginia Water, Ascot, Binfield and some parts of Bracknell. For other areas, including Windlesham, Lightwater and Bagshot, the number of departing aircraft over them has reduced. This change does not affect areas to the east of the airport such as Teddington, East Molesey and Twickenham, and it also does not result in aircraft flying over new areas. It applies to one departure route only, so arrivals are not affected.

While the change to procedures made by NATS is unrelated to the airspace trials that took place last summer and finished on 12th November 2014, it does affect some of the same residents - specifically in Ascot and Bracknell.

Following the ending of the trials, Heathrow was approached by a number of residents and their elected representatives with concerns that flights were being routed differently. Heathrow asked NATS whether there had been any other relevant changes to airspace and were told that no changes had taken place. However as a result of further investigations by NATS and the CAA, the procedural change was identified, affecting air traffic in areas to the southwest of the airport.

There is no suggestion that NATS had any intention to mislead; however their failure to identify this change to Heathrow resulted in the airport wrongly telling residents in good faith that no changes had occurred following conclusion of the airspace trials in November. Procedural changes made to the control of aircraft above 7,000 feet do not involve airports and there is no suggestion that NATS did not follow the current agreed process. Nevertheless where procedural changes occur that may have a discernable effect to the noise experienced by residents, we would expect NATS to make us aware of the changes and their potential impact so that we can answer questions from local residents.

In light of this NATS has agreed to urgently review the way it shares information with Heathrow on any changes which may have a discernable impact for communities living around Heathrow. The airport asked NATS to consider reverting to the prior operational procedures on Easterly departures. They have advised us that this change was made to improve the safe and efficient management of traffic departing from Heathrow and are not planning to revert.

For its part, Heathrow will continue to push for greater transparency from the aviation industry to promote trust amongst stakeholders and residents. Heathrow has recently set up the Heathrow Community Noise Forum which brings together local community representatives, councillors, and NATS, the CAA and DfT. This will be an important platform to address matters like this.

Heathrow CEO John Holland-Kaye said:

“I am very concerned that NATS made this change without informing the airport or affected communities about its potential impact, particularly given its effects on some of the same areas to the west of the airport that were affected by the airspace trials we ran last year. Because of the assurances we received, we in turn told residents in good faith that no changes had occurred. That is unacceptable and I unequivocally apologise to local residents.
At my request, the Chief Executive of NATS has agreed to urgently review his company’s processes to ensure that NATS shares this information with the airport to prevent this happening again in the future.”

View maps for before and after NATS made a procedural change affecting the Compton route

Download the map (790KB PDF)

Summary

The procedural change:

  • affects departures using one route on easterly operations
  • does not affect departures using the other five routes on easterly operations
  • does not affect departures on westerly operations
  • is unrelated to the airspace trials

Q & A

What were these changes and when were they introduced?

This was a procedural change introduced by NATS on 27 June 2014. The change affects the way aircraft are directed on one of the departure routes, known as Compton, when the airport is on easterly operations (i.e. when there are easterly winds). The airport is on easterly operations approx. 30% of the time.

The Compton route is one of six departure routes used when the airport is on easterly operations. The route concerned is used only for departures which turn to the West. In total it was used by 6% of all Heathrow departures in 2014. During periods of easterly operations, it is used by approx.16% of departing aircraft.

What has been the effect of these changes for people on the ground?

Aircraft are being directed by controllers through a more defined area within the existing airspace. Prior to the change, aircraft using the Compton departure route were directed across a wide swathe of airspace (approx. 13 miles) before moving into the next sector of ‘higher level’ airspace ( at approximately 8,000ft) via a “gateway” near Compton (hence its name) . Since NATS made the procedural change, this gateway for departures has been narrowed to around 7 miles which means that aircraft are now climbing through a narrower area of the existing airspace in order to be in the right place to go through the gateway. This has resulted in more concentration of departure aircraft activity over some areas and a reduction in others. It has also altered the position of some flights before they reach 7,000 feet, but not below 4,000 feet.

Because aircraft are now being directed through a more defined area and with less interaction with arriving traffic, aircraft are able to climb higher more quickly.

Why was this change made?

NATS has informed us that this change has enhanced safety and efficiency; the position of traffic in this airspace is more predictable for controllers, and by directing departures through a more defined area there is less interaction with arriving traffic. Departing aircraft had previously been kept longer at 6000ft while they were below arriving aircraft, but are now able to climb higher more quickly.

What height are aircraft affected by this change?

The change itself is at approximately 8,000ft (it may be higher, depending on barometric pressure). In order to be in the right place by that height, the position of some aircraft will be affected at lower altitudes on the Compton route.

What areas are affected by the change?

The main areas affected by this change include Virginia Water, Ascot, Binfield and parts of Bracknell.

The procedural change did not affect areas to the east of the airport such as Teddington, East Molesey and Twickenham.

For some areas the number of departures have reduced. This includes Windlesham, Lightwater and Bagshot.

Why didn’t NATS tell you about these changes?

This particular change applies above 7,000ft and airports are not involved in these changes. Nevertheless where procedural changes occur that alter the traffic patterns over communities close to the airport, we would expect NATS to make us aware of the changes so that we can answer questions from local residents.

On this occasion NATS did not highlight to us the change for aircraft using the Compton route and did not inform us of it when Heathrow asked them to confirm whether anything else had changed following the cessation of the airspace trials on 12 November. This resulted in Heathrow giving inaccurate information to local residents and stakeholders. NATS has apologised for this and steps are being taken to ensure it does not happen again.

How did Heathrow discover these changes had been made?

Following the ending of the trials, Heathrow was approached by a number of residents and their elected representatives with concerns that flights were being routed differently. As a result of further investigations by CAA and NATS, the procedural change that dates back to 27 June 2014 was identified which affects air traffic in areas to the southwest of the airport.

Are these changes related to the recent airspace trials?

No, this procedural change is unrelated to the airspace trials that operated last summer and finished on 12 November. The procedural change was introduced to enhance the safe and efficient management of traffic departing from Heathrow on the Compton departure route.

Has this change had any impact to the position of aircraft arriving in the vicinity, either height or position?

This is a procedure change for departures, not arrivals and so there should be no change to the pattern of arriving aircraft. The analysis of flight patterns doesn’t show a change to patterns of arriving aircraft since the procedural change was made to departures.

Are there are other changes to procedures that NATS has introduced that you’re not aware of or that may have had an impact for residents living around Heathrow?

NATS has confirmed there are not

How will you and NATS be communicating to residents about this change?

We asked NATS to consider this. They have advised us that this change was made to improve the safe and efficient management of traffic departing from Heathrow and are not planning to revert back.

Have you called for NATS to revert to the original procedures?

We asked NATS to consider this. They have advised us that this change was made to improve the safe and efficient management of traffic departing from Heathrow and are not planning to revert back.

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