London Heathrow's operator has put forward two options for a full-length third runway, to the west of the airport, to resolve the thorny issue of additional capacity for the hub.
The operator says the proposals for a 3,500m (11,480ft) runway, either to the north-west or south-west, are "radically different" options to the previously-considered notion of a short runway.
In a submission to the Airports Commission, set up to look at capacity options, the operator has retained a short-runway proposal - a 2,800m strip to the north.
But it points out that a runway located to the west would help cut noise by raising the height of the glidepath over the city.
"While there is still more work to be done on the precise detail, we believe they show why Heathrow should be included in the Commission's shortlist at the end of the year," it adds.
The full-length runways would raise annual capacity to 740,000 flights, more than the 702,000 offered by the short runway, and a 54% increase on the current limit.
All three runway options are "quicker and cheaper" than a newly-constructed replacement airport, costing £14-18 billion ($21-27 billion), and would provide additional capacity by 2025-29.
"Each option has its particular benefits, but Heathrow believes the two westerly options offer clear advantages," says the operator.
"They deliver a full-length third runway while minimising the impact on the local community from noise and compulsory house purchases."
Each full-length runway option would enable Heathrow to handle a total of 130 million passengers per year. The north-west runway would take "slightly longer" to build than a short north runway, while a south-west runway offers further benefits but is more costly and complex.