There was no legal strike but there was a legislation change which was going to be voted on this day of illegal strike.
Is it lawfull in your country that the union sends SMS messages at 11PM and says tomorrow we will all be sick and will not be fit to fly.
THY did send also SMS and mail saying that there is no legal background and people obeying this instruction will be fired.
All the pilots (including expats) were present for their flights but a lot of cabin attendants did not go to flying and beleive me only few flights were made that day from Istanbul untill afternoon.
I was going for my flight and the union did try to stop me from entering the airport. I sad to them "hey this is not legal. If there would be a legal strike things would have been different."
I think this video is prepared by the union which in my honest opinion did use innocent people for their interest.
The union could make other activities rather than not letting the aircraft fly.
I was reading a topic regarding cheap pilot utilization in Norway. There, the pilot union chief sad it is illegal to make a strike regarding this issue.
I am a pilot flying for THY and not a manager but I just wanted to reply so that you see this issue from both perspectives and not only unions.