BAA's managing director of London's Heathrow airport, who was responsible for assuring "cost, time, quality and safety" at Terminal 5, is leaving the airport operator with immediate effect.

Mark Bullock, who held overall responsibility for T5, is the third senior manager to depart since the terminal's disastrous opening on March 27, when hundreds of flights were cancelled and thousands of passengers’ bags were lost.

Last month, British Airways announced that Gareth Kirkwood, the director of operations, and David Noyes, the director of customer services, would be leaving the company.

BAA said today that Mr Bullock is leaving as part of a "structural change" already announced by the operator's new chief executive, Colin Matthews, who joined the company on April 1. However, less than a month ago, Mr Bullock was promoted to a new executive committee set up by Mr Matthews.

Mr Matthews said today: "Mark Bullock has made a significant contribution to BAA and to Heathrow Airport in particular and has led the airport through a particularly challenging period. I am grateful for his efforts."

Mr Bullock will be replaced by Mike Brown, currently the chief operating officer at London Underground, who will join the group in September. Until Mr Brown takes over, Heathrow's operation will be overseen by Terry Morgan, BAA's airport services director.

Mr Bullock said today: "Leading the team at Heathrow Airport is an intense and demanding role, but one I have enjoyed very much.

“The managing director role at the airport will change substantially under the new structure being introduced by Colin Matthews and, while I understand and support those important changes and the renewed focus on day-to-day operations, the time is clearly right for me to move on and take on new challenges.

"I wish my successor and everyone associated with Heathrow Airport every success in the future."

Mr Bullock first joined BAA in January 2004, as T5 programme assurance director where he was responsible for the "finance, commercial and risk management functions" as well as assuring "cost, time, quality and safety" at the yet to be opened new terminal.

Last year, Mr Bullock took overall responsibility for Heathrow when the previous chief, Tony Douglas, left BAA after calling the state of the airport "unacceptable", adding that it was "bursting at the seams" and was "held together by sticking plaster".

BAA, which is majority owned by Spain's Ferrovial, is currently struggling to refinance £10 billion worth of debt and last week secured £400 million in funding from investors to help enhance its credit rating that would help the company agree a cheaper rate of borrowing.

The difficulties with refinancing the debt means BAA may have to bring forward the sale of one its assets, potentially Gatwick, which could fetch at least £2 billion.

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