Flights to three Scottish airports have been hit by cabin crew strike action at British Airways after talks between BA and the Unite union collapsed.
The three-day walkout began at midnight, with a further four days of action set to commence on 27 March.
The dispute has affected a number of flights to and from Edinburgh, Glasgow and Aberdeen airports.
Passengers travelling on the affected days have been advised to check details on the British Airways website.
British Airways chief executive Willie Walsh said the strike was "deeply regrettable".
Unite's joint general secretary Tony Woodley said that BA "ultimately wants to go to war with this union".
The dispute centres around working hours and annual pay rise offers in exchange for the cabin crew workers agreeing to BA's planned £62.5m of cost cuts.
A total of 1,100 BA flights out of the 1,950 scheduled to operate during the first three-day strike were expected to be cancelled.
But the airline has said 65% of passengers would reach their destination during the action.
Seven British Airways flights at Edinburgh Airport were due to go ahead, 12 flights were scheduled.
On Sunday 21 March, 15 flights were scheduled with seven due to go ahead. On Monday 22 March, 19 flights were scheduled with 10 due to go ahead
At Glasgow airport, nine flights were scheduled and five were due to go ahead. On Sunday 21 March, 12 flights were scheduled with six due to go ahead.
On Monday 22 March, 15 flights were scheduled, eight were due to go ahead.
At Aberdeen, five BA flights were scheduled - five will go ahead. On Sunday 21 March, six flights were scheduled, three were expected to take off.
Nine flights were scheduled on Monday 22 March, but only four will go ahead.
At Gatwick, all long-haul flights and more than half of short-haul flights were expected to operate as normal.
At Heathrow, more than 60% of long-haul flights will operate, though only 30% of short-haul flights were expected to go ahead, with the help of aircraft leased from eight rival airlines.
Mr Walsh said: "Tens of thousands of BA people stand ready to serve our passengers and BA will be flying and will continue to fly through these periods of industrial action."
He added that he remained available for talks on reaching a "sensible" agreement, but said that loss-making BA must cut costs.
Mr Woodley had called on BA to put an earlier deal to end the strikes "back on the table" - a move he said would allow him to call off the strike while union members considered it.