LONDON -- A difficult period in the history of the "world's favorite airline" came to an abrupt conclusion this morning when Bob Ayling, British Airways' (BAB) - Get Report chief pilot, bailed out of the company he has headed for the past four years.

Long-suffering investors have seen 40% of BA's valuation wiped out since Ayling took the controls, and the market welcomed his departure with a 15p rise in the share price to 308p. British Airways was lately trading up 7.5p, or 2.6%, at 300.5. Shares of British Air, which had traded above 88 last spring, closed at 46 1/16 in New York on Thursday.

It appears that Ayling's departure was a mutual agreement between him and the board, although the beleaguered former chief executive said he wishes to spend more time with his family.

The hunt for a replacement is now on, but in the meantime, Lord Marshall, who stepped up to be BA chairman to make way for Ayling's elevation, will add the chief executive's role to his responsibilities.

Sir Richard Branson, Ayling's archrival at

Virgin Atlantic

, was swift to offer his condolences. "It is never pleasant when someone has to leave a company they have worked with for years, and I do wish Robert Ayling the best of luck in the future," he said.

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However, it was Branson who was a thorn in BA's side for more than a decade, and Virgin's success in winning market share on the key trans-Atlantic routes has compounded the more general industry problems with which Ayling has had to grapple. In the first half of Ayling's tenure, Virgin increased its market share of routes to five out of six U.S. gateway destinations and increased its overall passenger traffic by around 50%.

Other things have gone wrong for Ayling. His grand plan of an alliance with

AMR's

(AMR)

American Airlines

had to be scaled down, and he was heavily criticized for dropping the Union Jack from the BA fleet's tailfins and replacing them with "ethnic" designs.

The overcapacity in the airline industry also forced him to undertake cost-cutting measures, which pitted him against the unions, and he had to endure a damaging cabin crew strike.

Ironically, many agree that Ayling's answer to BA's problems -- to cut capacity, buy smaller planes and focus on the business-class segment of the industry -- was correct. Unfortunately for Ayling, he won't be around to see if he was right.