British Airways pilots on Monday slammed the "arrogance" of the airline's board in its chaotic handling of London's new Heathrow Terminal 5 and said they wanted change in how the company was managed.

Baggage and staff familiarisation problems have forced BA to cancel hundreds of flights from the 4.3 billion pound ($8.55 billion) T5 since it opened on March 27.

In an open letter, the British Airline Pilots' Association (BALPA) called on the British government and financial institutions to "act" on how the carrier was being led.

"It is with great sorrow and acute embarrassment that BA pilots have witnessed the unhappy, distressing shambles that the opening of T5 has become," BALPA said in the letter.

"We want confidence in our leadership, not arrogance," it said.

BA said in response that Chief Executive Willie Walsh would not resign and was "determined to resolve the problems associated with the initial move to Terminal 5".

BA cancelled another 34 flights on Monday as it battled to clear a backlog created by bad weather from a snow flurry on Sunday.

Heavy snow on Sunday morning forced BA to cancel around 140 flights at T5 as runways were de-iced and air traffic control reduced the number of take-off and landing slots.

BALPA said it had pressed management for a number of years over issues including punctuality and baggage delivery.

"Banks, institutional investors and analysts need to wake up to the fact that there is something very wrong right at the heart of this company that is making our once great brand a laughing stock," it said.

In February BALPA agreed to enter into arbitration with management after pilots had earlier voted to strike in a dispute over employment terms at a new subsidiary.

BA narrowly averted a costly 48-hour strike a year ago by cabin crew by agreeing new working conditions.