STRIKE – Air traffic safety workers plan to strike from September 23- 27 at 5 airports in Greece. Reconfirm flight status with airlines.
https://www.public.nm.eurocontrol.int/PUBPORTAL/gateway/spec/index.html
Another source:
Air Traffic Safety Electronic Engineers Association of Hellenic Civil Aviation:
work stoppages on Friday from 11:00 to 15:00, and 19:00 to 23:00
from Saturday 24 to Tuesday 27/09: from 3:00 to 7:00, 11:00 to 15:00 and 19:00 to 23:00
on Wednesday 28 and Thursday 29/09: 24 – hour strikes.
This might affect some regional airports
http://www.livinlovin.gr/strikes-work-stoppages-in-greece-updated/