The Irish businessman will stand down from the role of chief executive and give up his seat on the IAG board on 26 March 2020, and will officially retire on 30 June 2020.
His arch-rival, Michael O’Leary of Ryanair, led the glowing tributes: “Willie Walsh will be a huge loss to IAG and to the airline industry.
“His drive and vision has transformed both IAG and European airlines for the benefit of passengers everywhere. He has repeatedly proven that ‘you’ll never beat the Irish’. We wish him continued success for the future.”
There is some surprise that Alex Cruz, chief executive and chairman of British Airways, will not replace him. Mr Cruz was widely seen as Mr Walsh’s protege.
Rob Burgess, editor of the frequent flyer website headforpoints.com, said: “British Airways may not be popular with the public but it is, financially, remarkably successful.
“With BA remaining the dominant part of IAG, perhaps there was a reticence to disrupt Alex Cruz’s ongoing transformation of the business.”
Instead, the top job at IAG boss will go to Luis Gallego, who has been Iberia’s chief executive since 2017. He said: “It is a huge honour to lead this great company. It is an exciting time at IAG and I am confident that we can build on the strong foundations created by Willie.”
Mr Walsh said: “Luis has been a core member of the team and has shown true leadership over the years and I have no doubt he will be a great CEO of IAG.”
Antonio Vazquez, IAG chairman, said: “Willie has led the merger and successful integration of British Airways and Iberia to form IAG.
“Under Willie’s leadership IAG has become one of the leading global airline groups.
“I am deeply respectful of what he has achieved as CEO of this Group, of his sense of fairness, his transparency and his capacity to integrate people regardless of nationalities or backgrounds.”
Mr Walsh, 58, began his career in aviation in 1979 as a 17-year-old cadet pilot at Aer Lingus.
In 2001, he became chief executive at the Irish airline – as it faced intense competition from its rival at Dublin airport, Ryanair.
He is credited with turning Aer Lingus around financially, though there was disquiet at the scale of the job cuts he imposed.
British Airways took him on as chief executive in 2005. He set about cutting costs, by slimming down management and increasing productivity.
The high point of his career should have been the opening of Heathrow Terminal 5 on 27 March 2008, intended as BA’s dedicated hub. But within hours the airline’s operations collapsed, leading to the cancellation of hundreds of flights.
As the global financial crash of 2008-9 hit the airline industry, Mr Walsh clashed with the cabin-crew union, Unite, over pay and job cuts. A long and bitter dispute ensued, which included the union calling a 12-day strike over Christmas 2009 – later overturned by the High Court over ballot irregularities.
After a series of shorter strikes, the two sides agreed to the creation of a new, lower-cost group of cabin crew known as Mixed Fleet.
In 2010 Mr Walsh led the airline industry’s response to the Icelandic volcanic ash closure of airspace – flying an empty Boeing 747 to support his argument that the passenger flight ban was an overreaction.
He became the chief executive of IAG in 2011 when British Airways merged with Iberia to form the new company.
In 2015, IAG acquired Aer Lingus.
Since the expansion of Heathrow was given the go-ahead, Mr Walsh has been a vocal opponent of the costs proposed by the airport.