The Unite union, currently engaged in a bitter cabin crew dispute with British Airways, will be handing out letters to shareholders attending tomorrow's annual meeting of the airline.
The letter urges management to end its "fixation with conflict" over a dispute which has already cost BA around £150 million.
It is thought that Unite could be joined in the protest in Westminster by a delegation from a Spanish union representing workers with the Iberia airline whose merger with BA is expected to be completed in the next few months.
BA cabin crew have staged a series of strikes since March and are currently being balloted on a fresh offer from BA.
The airline has said the new offer addressed crews' concerns about future earnings and included a firm commitment that staff could keep current pay and conditions.
Unite is making no recommendation on whether to accept or reject the proposed deal.
Last year, Unite hired lemmings for a protest outside the annual meeting venue but the animals were taken away after an RSPCA inspector said they showed signs of "distress".
Meanwhile, BA today became the first UK airline to take delivery of the long-range Boeing 777-300ER aircraft, which is longer, quieter and more fuel efficient than its predecessors.
The 297-seater plane will go into service later this year. BA will take delivery of two more of the aircraft by the end of this year and three more by early 2012.