London Heathrow airport is reiterating the case for a third runway as it rejects the permanent employment of mixed-mode operations, while the UK hub plans to "marginally" improve runway utilisation for greater reliability without increasing traffic volume.
"The only realistic solution" to create capacity for additional flights at the UK hub is to build a third runway, says Heathrow in a submission to the Howard Davies-chaired Airports Commission looking into future airport capacity.
Using the existing two parallel runways for both arrivals and departures throughout the day - as has been trialled in temporary mixed-mode operations in 2012 - would only increase capacity "incrementally" whilst local communities are subjected to "significantly" more noise, it adds.
When aircraft approach Heathrow from the east, across central London - which is currently being prioritised whenever possible under prevailing winds - the airport uses one runway for arrivals and the other for departures. Their use is swopped at 15:00 to set periods with less noise for local residents under the flight path.
Introducing permanent mixed-mode operations "comes at a significant cost to the local community because it would end periods of respite from noise", says Heathrow.
Instead of creating capacity for additional traffic, the airport plans to change operating procedures and airspace utilisation for "marginal" capacity increases to improve airport resilience at the current traffic level, which is capped at 480,000 flights a year.
Heathrow wants to start using the northerly runway for takeoffs toward the east - this is currently being done from the southerly runway - and operate with eastbound departures and respective approaches from the west, across Windsor, more often. The airport has proposed to end the policy of westerly departure preference.
Although the plan will only go ahead if UK air traffic service provider NATS will conclude "that this would deliver a noise benefit for residents without compromising operational performance" in an assessment, Heathrow adds. If this is successful, departing aircraft will need to be quickly diverted from residential areas through early vectoring.
The airport also wants to use both runways more flexibly for approaches from the west. Flights arriving at Terminal 4 would thereby land on the southerly runway to shorten taxi distance and avoid runway crossings on their way to the gate. Airbus A380 flights would also touch down on the southerly runway.
The number of early morning arrivals between 5:00 and 6:00am is to be increased. The airport says that the additional traffic would be handled on one runway, while current regulations permit the use of both runways between 6:00 and 7:00am.
Heathrow also wants to handle arriving aircraft based on their scheduled flight times and not under the current 'first, first served' basis.
Under the revised operations, the airport says, it would be able to spread all flights across a greater number of routes that provide resident "predictable periods of respite" from noise.
The Airports Commission was set up by the UK government in November to study the thorny issue of the UK's need for additional airport capacity. It will report at the end of this year on moves to improve existing runway capacity over the next five years and the longer-term capacity needs by summer 2015. As part of this process it has just released the fourth of a series of discussion papers considering the distinguishing features of a hub or focal airport.