So today i was doing a flight from LEPA to EDDF, and mid-way, all of EDDF control went offline, i thought about diverting to my alternate or a close airport but i ended up just not doing it. And know i am wondering, are you allowed to divert just because you want to (Ex: i want to arrive in controlled airspace)
Yes, you can. If you are with ATC, ask them to amend your ATC-flightplan. If not, just change course and proceed to your alternate.
when you say “just change course” do i just fly a heading or do i reroute on the FMC. And when i arrive in controlled airspace, do i ask the tower to Amend my flight plan?
I think of it from the perspective of what ATC would likely issue me if they were online. They’ll issue you a new clearance and route, if applicable, all of which you would put into your FMS. In your case, with no ATC online, you could certainly set yourself up on a direct course to your alternate airport, then determine which arrival procedure, if applicable, as well as which approach you’d like to set up for, based on the ATIS.
Once you’re in touch with the tower controller, you’d probably want to mention you diverted while in uncontrolled airspace so they have the chance to update the flight strips, otherwise they’ll most likely have some questions for you.