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  • No 3rd Runway Coalition

Mixed mode means Heathrow Expansion through the back door

Since 6th April, Heathrow has been operating using only one runway, in mixed mode, as a result of significantly reduced flight numbers during the COVID-19 pandemic. Mixed mode means landings and take-offs can take place on the same runway. At the moment this will be alternated each week, starting on a Monday.

The mixed mode operations will be in both directions which means those who live close to the northern runway or under its flightpath will experience both landing and take-off noise. The latter will be most intrusive as due to the long-established Cranford Agreement take-offs have not previously been permissible.

Campaigners are concerned that the use of mixed mode during the pandemic may in fact pave the way for how Heathrow might seek to operate its airport in the future.

There are two main reasons why these concerns are not unfounded. First, Heathrow expansion is looking less, not more likely, as a result of the Court of Appeal’s ruling in February. The ruling stated that the Government had not considered legally binding climate change targets when presenting the Airports National Policy Statement to Parliament. Heathrow have sought leave to appeal this ruling, but the Supreme Court is yet to state whether they will grant an appeal.

Second, if Heathrow does not get its third runway, it is likely they will be looking for a some form of expansion in its “two-runway strategy” that it is expected to launch in due course. This could take the form of increasing the annual cap on flight numbers from its current threshold of 480,000, to a new figure, over 550,000. This would be possible if the airport were to operate using mixed mode. For communities around the airport this would mean either a significant reduction or an end to the current alternation which provides half a day’s break from aircraft noise.

When Heathrow were seeking to introduce mixed mode in the 2000s, it was estimated that flight numbers could increase to 540,000 per year. Improvements in aircraft technology since then could enable that figure to increase further. Heathrow is currently operating using 98% of the current threshold – 476,000 flights each year, so mixed mode could increase the number of flights at Heathrow by a minimum of 75,000 every year.

There would likely be a public inquiry on whether to allow mixed mode, as the local planning authority – Hillingdon Council – will oppose any increase in the number of flights per year at the airport. It is not certain whether the Government would support any application for an increase in flights in this way: they could suggest it is a ‘compromise’ if it rules out a third runway. This would, of course, be politically toxic in the areas around Heathrow and under its flight paths, as many hundreds of thousands of people rely substantially on the current half day’s break from aircraft noise.

Nevertheless, the scale of any proposal for mixed mode operations would be clear: at least 200 more flights every day at Heathrow. Such an uplift would present a neat consolation prize for Heathrow if they cannot get a third runway, but would bring misery to the 725,000 people already blighted by aircraft noise. Mixed mode means Heathrow expansion through the back door and it should be opposed.

Rob Barnstone

Co-Ordinator, No Third Runway Coalition

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Apr 30, 2020


you must consider in your publications/blog that Windsor town six miles from landing, when on easterlies, we currently experience up to 18.5 hours of constant landing traffic overhead from 0442 to past 0001 hours and some southern runway use as well, albeit 33% pa.

The Cranford agreement has been passed at planning appeal. Flip to westerlies we get 100% of takeoffs with only a narrow channel protected by NPR.

Surprisingly HAL would not allow departures on the northern runway due to flight space but they are now. Many departures are not adhering to 09L NPR and going straight ahea, one seen at 10,000 ft over Central London.

so please consider the a RBWM perspective for noise relief.



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