According to the VC twitter account, they did go on strike, but a lot of the flights left on time, crewed by contractors and people from other bases.
Before you all start shouting scabs, remember one thing: in most countries in Europe sympathy strikes are unlawful, and as such, if you're called in to work for strikebreaking purposes in another country, you have no choice but to go to work. Refusing to work will most certainly land you in hot water with the employer, and will also compromise the unions who will most likely be facing a courtcase for inciting unlawful industrial action!
Make sure you know the facts before accusing anyone for 'crossing the picket line'!