SimBrief

https://www.simbrief.com/

SimBrief is another great online service. It is powered by Navigraph. Is focused on flight planning and everything, that is related to it. It include detailed fuel calculations for over 120 aircraft types, an extensive route database, real-world weather forecasts, current NOTAMs, ETOPS planning, and much more! It is FREE, but slightly limited in this mode. It will only allow you to use some older (outdated) AIRAC cycle for computing the flight route, but you can use otjher services for that. If you have Navigraph subscription, you will be able to use the latest cycle. The flight planning is there very fast and you will get all the required information at one place. You can export the flight plan to many formats and some aircrafts also support to import the flight plan directly from your SimBrief account.

FsHub

https://fshub.io/

FsHub is a free cloud service that provides virtual pilot and airline flight tracking and performance monitoring for Microsoft Flight Simulator 2020, X-Plane, Prepar3D, FSX, FSX:SE and FS2004! That is the official saying, and I would add it is wonderfull free service. Also offers many “achievements” to give you more reasons to soar the virtual skies and visit places you maybe did not know about existing.

Live ATC

https://www.liveatc.net/

Here you can listen communication between real world pilots and air traffic controllers. Many airports from all over the world are listed, including Václav Havel airport – LKPR.

Flight Radar 24

https://www.flightradar24.com/

Great page for aviation enthusiast. You can watch real air traffic almost in real time. You can view flight path, altitude, airspeed, origin and destination and even photo (if someone ever took a picture of that particular aircraft) for every displayed airplane.

Windy

https://www.windy.com/

This website offers awesome wind prediction in the form of simple animation. You can see what the wind is to be like on the whole planet and at various altitudes. And not just the wind, you can view temperature, pressure, humidity, clouds, precipitation and also waves.

Skyvector

https://skyvector.com/

This site contains VFR and IFR aviation maps. In the beginning, only the USA and Alaska were covered, but the coverage grown worldwide. Very good source of charts, which is also free.

VACC Czech Republic

https://www.vacc-cz.org/

The czech “division” of VATSIM for virtual air traffic control over Czech Republic. You can find info about upcoming actions, steps to connect to VATSIM, how to behave on network etc. Site is available in Czech and English.