ATC strikes are planned in Portugal on 11th, 17th, 18th, 24th and 25th of May.
3 strike periods daily as follows:
06h00 to 08h00 / 13h00 to 15h00 / 20h00 to 22h00 ( UTC)
Strike dates and times are confirmed by NOTAM.
http://www.nav.pt/ is the responsible organisation.