British Airways pilots have voted to go on strike in a row over pay and conditions.
And they have warned the airline will be grounded if industrial action goes ahead.
The British Airline Pilots Association (Balpa) said its members voted by 86% in favour of walkouts in a dispute over BA's new subsidiary carrier OpenSkies.
The union claimed pilots in the new airline would be on lower pay rates and worse conditions, charges BA denied.
Balpa, which represents around 3,000 BA pilots, said turnout in the ballot was 90%, which the union said reflected the concern of its members.
Any strike by pilots would be the first for almost 30 years and would threaten to disrupt flights over Easter.
Balpa said it supported the growth of BA and the launch of the OpenSkies service but claimed the airline intended to hire lower-paid pilots recruited from outside.
BA plans to keep their wages low even when OpenSkies becomes profitable, said Balpa, adding pilots feared that pay and conditions for OpenSkies pilots would be used to force down their own pay and conditions.
General secretary Jim McAuslan said: "We have seen it happening around the world. BA pilots are determined not to let the same thing happen to them and to their families. That is why Balpa has drawn a line in the sand. BA pilots are saying loud and clear that they will not tolerate what has happened elsewhere."
BA said: "We have guaranteed to Balpa that OpenSkies does not represent a threat to the terms and conditions of BA pilots. We have offered to make these guarantees part of our industrial agreements with pilots."
