British Airways dismissed two of its longest-serving managers yesterday for their part in the shambolic opening of Terminal 5 at Heathrow, as Willie Walsh, the chief executive, acted to deflect demands for his own resignation after more than 500 flights were cancelled and 28,000 bags were lost.

BA announced that Gareth Kirkwood, the operations director, and David Noyes, the customer services director, would be “leaving the company” and that their departures “follow the airline's move to Terminal 5”. Each had been employed by BA for more than 20 years.

The announcement came only four days after Mr Walsh had said: “If people want to assign blame for this, it comes to me.” Mr Walsh, who joined BA three years ago, had also said that there was “little value or merit in trying to apportion blame”. On Monday, however, BA came under renewed pressure to take action when Standard Life Investments, a key shareholder, discussed the T5 debacle at a meeting with Martin Broughton, the BA chairman.

Senior members of Balpa, the pilots' union, have called for Mr Walsh to resign over the mishandling of the opening. He still has the support of the City, but some investors have said privately that much depends on how he performs in the next few months.

Douglas McNeill, a Blue Oar Securities transport analyst, believes that the dismissals might not stem the calls for Mr Walsh to resign. He said: “The announcement of the two departures is intended to relieve the pressure on the company and on Willie Walsh. It may not do so.”

It took BA almost two weeks to operate a full service at T5. Staff had not been trained properly to use the new baggage system and there were also glitches in the software that controls it. BA announced last Friday that the transfer from T4 to T5 of 120 daily long-haul flights, planned for April 30, would be postponed until June. It emerged this week that the transfer might be not be completed until October, disrupting the schedule for upgrading Heathrow's older terminals.

BA said ten days ago that the problems at T5 had cost it £16 million in lost revenue and compensation, though the final cost is expected to be higher. The carrier said that it intended to appoint a chief operations officer to combine the roles of the two executives who were leaving.

Mr Noyes, who joined BA in 1985, had been involved with T5 for about three years. He gave a series of pledges about how successful the new facility would be in a press briefing two weeks before it opened. He said: “We are confident that this building is operationally ready.”

BA lost 28,000 bags in the first four days of T5's operation, and thousands of passengers are waiting to be reunited with their bags. Some insurance companies are refusing to cover passengers for lost luggage or cancellations at T5 if they have taken out new policies since the terminal opened.

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