These guys have multiple issues to sort out with the management and have been trying to sit across the table to sort them out since past 2 years. They even had their grievances brought to the new aviation ministers notice, but have run out of patience.
Career progression, pay disparity, duty hours, cut in wages, delayed wages, deferred increments are just some of them. Management's indifference has forced the issue on the pilot body to take this drastic step.
Don't blame them entirely. There is a limit to which something can be stretched before it snaps!
Aeronotix