How do I know which airports are being opened on a given day?
For expert server, we have a weekly dedicated ATC schedule that dictates what airports will be opened throughout the day:
But for example, not all the airports on the ATC schedule are open today
It’s a guessing game really!
Though, if you’re looking for an airport that’ll be most frequently controlled throughout the day, typically it’ll be the featured airport//hub that has the most inbounds due to a range of factors; eg popularity, destinations, routes etc etc. With IFATC being voluntary though, unfortunately we can’t always ensure that all featured airports will be staffed non-stop throughout the day. They’ll always be prioritised though :)
There is also the list at https://www.ifatc.org/ with status for each aerodrome in the schedule.
When planning flights it may also help you to know that there are minimum opening times on Expert: 30 minutes for class Charlie and 60 for class Bravo.
It’s also worth noting that IFATC are voluntary and may choose whether or not to open a featured airport on a given day.