Speaking at a press conference today to celebrate the milestone, Willie Walsh, who is the chief executive of IAG which owns the Irish flag carrier, said the airline was currently focusing on making a success of its move to compete heavily on transatlantic routes.
But he admitted the option for the airline to rejoin the alliance which it left in 2007 was on the table.
Walsh said: "Aer Lingus certainly will consider it. At the moment our focus is on the transatlantic market… but Aer Lingus would certainly like to look at the oneworld alliance again, and given the way oneworld is I think that’s a very realistic proposition.
"One of the reasons Aer Lingus left the alliance was because of the complexity associated with being a full member, which was difficult at the time."
The alliance was launched in 1999 by American Airlines, British Airways, Cathay Pacific and Qantas and currently has 13 members. Royal Air Maroc will join in 2020 while Fiji Airways will be fully implemented as a oneworld connect partner next month.
Walsh also admitted in the press conference that he could be interested in buying more A380s for BA as Emirates seeks to row back on an order for 20 of the aircraft, providing the price was right.
He said: "I’ve no concerns about the A380, we’re very pleased with the 12 that BA operates and it’s been an excellent aircraft for us.
"We’ve made it clear to Airbus that we might consider some additional aircraft but it would have to be at a prices that we found attractive."
Walsh also argued that Heathrow will remain a key airport for the world’s airlines no matter what the outcome of Brexit was, although he added he was confident a deal would be agreed between the EU and the UK.
However, he again warned the airport that it could not use the third runway as an excuse to increase fees.
Walsh added: "I don’t think it [Brexit] is going to have any impact on passenger numbers. I remain confident that we will see a comprehensive agreement."
