BAA’s managing director of London’s Heathrow airport, with responsibility for the launch of Terminal 5, is leaving the airport operator.

Mark Bullock, who was responsible for assuring “cost, time, quality and safety” at Terminal 5, is the third senior manager to leave since the T5’s troubled opening last month. Hundreds of flights were cancelled and thousands of passengers’ bags were lost.

Last month, BA announced its director of operations Gareth Kirkwood and director of customer services David Noyes would leave the airline.

BAA said today that Bullock was 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.

Bullock, who has been with BAA since 2004, will be replaced by Mike Brown, who is currently the chief operating officer at London Underground, who will join BAA in September.

Bullock said: “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.”

BAA chief executive Colin Matthews said: “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.”