Unite, the union representing British Airways' cabin crew, has not informed the airline if or when it intends to strike, but CEO Willy Walsh assures flyers that a strike would not ground BA.
Walsh said there are 6,000 volunteers ready to step in, and that nearly 1,000 of them have been trained as cabin crew.
Len McCluskey, Unite's assistant general secretary, said Walsh has chosen to adopt an "inflammatory and confrontational stance at a time when we are engaged in meaningful talks with the company."
"Again, we say to BA that the only way to resolve the issues before us is through negotiation," McCluskey said. "They certainly will not be addressed by attempting to intimidate employees."
Unite must tell British Airways by March 15 if it intends to strike, and it cannot strike without giving the airline seven days' notice.
In the event of a strike, BA said it would operate all flights from London City (including recently launched service to New York), all long-haul flights from London Gatwick and about half of its short-haul flights from Gatwick.
At London Heathrow, BA said it would operate "a substantial proportion" of long-haul flights and "a good number of short-haul flights," assisted by chartered aircraft with crews from other airlines in the U.K. and Europe.
"We have also arranged to secure seats from other carriers, so thousands more of you can reach your chosen destinations," Walsh said.