Aer Lingus could cut at least £10m (€13m) from ticket costs overnight after Heathrow Airport revealed plans to slash its passenger charges.
Heathrow has unveiled proposals to slash fees for passengers travelling in and out of the world's third biggest airport. It plans to cut charges by £5 for European passengers and £10 for domestic passengers. This will cut the cost it levies on people flying between Ireland and Heathrow to £24.59 (€33).
The move should immediately lower costs for the two million passengers Aer Lingus flies in and out of Heathrow every year, provided it passes the savings on. Aer Lingus flies to Heathrow from Dublin, Cork, Shannon and Belfast. The savings will be even bigger for Belfast flights, since Belfast to Heathrow is a domestic UK route. The savings would begin from the start of next year.
However, not all of Heathrow's proposals will lower costs for Aer Lingus.
The airport is also planning to double its charges for airlines for nitrogen dioxide and nitric oxide emissions in a bid to encourage airlines to use newer, quieter and greener aircraft.
Aer Lingus will have a chance to reject the proposals. The Irish carrier, alongside British Airways and Virgin's Little Red, must give its approval to the plans, because it is one of Heathrow's top three providers of regional flights.
Dublin Airport could potentially lose out from the move.
Heathrow's efforts are an attempt to claw back traffic from rival hub airports in Europe, such as Dublin, experts said. It has been losing custom to rival hubs such as Ireland's biggest airport and Amsterdam Schiphol for several years, as these hubs are cheaper and easier to make long-haul connections through.
Aer Lingus's potential takeover by aviation giant IAG, meanwhile, has yet to see white smoke.
Weeks of discussion over IAG's €1.4bn bid have failed to produce an outcome. Debate has centred on IAG chief executive Willie Walsh's plans for Aer Lingus's 26 Heathrow runway slots .
Last week Virgin Atlantic, the carrier founded by Richard Branson, intervened in the row over whether the Government should offload its 25pc stake, insisting that Irish consumers will lose out if the sale proceeds.
An agreement allowing Aer Lingus passengers to transfer seamlessly on to long-haul Virgin Atlantic routes could disappear if the IAG bid is sealed, Virgin warned.
2 million - The number of people Aer Lingus flies to and from Heathrow every year
€1.4bn - Offered for the airline by British Airways owner IAG
26 - Heathrow runway slot pairs owned by Aer Lingus