VATSIM and IVAO: flying online with virtual air traffic control

Out at the fence, you listen in as the tower clears an Airbus to land. At home at your desk, you can play out that scene yourself – as a pilot in the cockpit or as a controller at the radar screen. That’s exactly what VATSIM and IVAO are for: two worldwide networks that connect thousands of flight simulators into one shared airspace and put real people at the virtual radios. This guide explains how the two networks are set up, what sets them apart, what software you need and how to make your first online flight without stress.

VATSIM and IVAO: the short answer

VATSIM and IVAO are free, nonprofit networks for online flight simulation. Through a small add-on client, your simulator logs in to a server. Other pilots then see your aircraft at its position, and volunteers act as virtual controllers providing air traffic control – with clearances, taxi instructions, radar vectors and radio communication. Both networks pursue the same goal: procedures that come as close as possible to real aviation.

If you haven’t set up a simulator yet, start with the guide Getting started with flight simulation. Flying online only pays off once you can confidently operate your aircraft from gate to landing.

Where the two networks come from

The story begins in the late 1990s. Back then, sim pilots could fly online together for the first time using add-on programs such as SquawkBox, organized in the network SATCO. After a dispute over leadership, a group of members left the project and founded the International Virtual Aviation Organisation, IVAO for short, on December 16, 1998. Since 2007 it has been registered as a nonprofit association under Belgian law and is financed through donations. Its motto is “As real as it gets.”

SATCO itself became the Virtual Air Traffic Simulation Network, VATSIM, in 2001. Since 2023, the operating body has been set up as a nonprofit organization in the US. By its own account, VATSIM has nearly 200,000 active members; IVAO reports more than 250,000 registered accounts, though a large share of them are inactive. Such figures are snapshots and fluctuate – what matters for you anyway is how much is going on in your region in the evenings.

How the shared airspace works

Technically, the principle is the same on both networks:

• The pilot client runs alongside your simulator, reads out position, altitude, speed and transponder code and sends them to the network. In the other direction, it draws the other aircraft into your scenery.
• The controllers work with their own radar software, see all connected aircraft with callsign and flight plan, and manage traffic at their position – from the apron to en route control.
• The radio runs via voice or text. Since 2019, VATSIM has simulated the range of real VHF radios with “Audio for VATSIM”: those far away become weaker and scratchier, as on real aviation radio.

If a position isn’t staffed, you still aren’t flying in a radio void. On VATSIM, the code of conduct says you then monitor the designated advisory frequency – if none is specified, that is 122.800 MHz (“Unicom”) – and announce your intentions there so other pilots know what you’re up to.

VATSIM and IVAO compared

If you only know the basic idea, it’s easy to think the two networks are interchangeable. In the details, they differ in software, structure and rating system.

Feature	VATSIM	IVAO
Founded	2001, successor to SATCO	December 1998, split from SATCO
Legal form	nonprofit, volunteer-run	nonprofit association under Belgian law
Cost	free	free
Pilot clients	vPilot, xPilot, swift	Altitude
Controller software	EuroScope, vatSys, CRC and others	Aurora
Structure	regions, divisions, local units (in Germany VATSIM Germany)	country divisions (in Germany IVAO Germany)
Pilot ratings	P0 to P4	FS1 to ATP
Controller ratings	S1 to C1, plus C3 and instructor ratings	AS1 to SEC

The old IVAO programs IvAp and IvAc have no longer been supported since January 2025; if you find older tutorials, make sure to look for the current clients. On VATSIM, something similar applies to some older radar programs that were replaced in 2023.

The structure in Germany, Austria and Switzerland

VATSIM assigns Europe to several divisions, the largest being VATEUD. Local units, so-called vACCs, work underneath. Germany, Austria and Switzerland used to be organized together; Austria split off at the end of 2008, Switzerland in March 2009. Since then, VATSIM Germany (also VATGER) has operated German airspace with the three flight information regions Bremen, Langen and Munich – just as in reality, where DFS Deutsche Flugsicherung (German air navigation service provider) is responsible. Austria and Switzerland have their own vACCs, analogous to Austro Control and Skyguide.

On IVAO, the regional units are called divisions. IVAO Germany organizes training, events and controller staffing for German airspace.

What you need for your first online flight

The barrier to entry is lower than many think. You don’t need a license or an expensive cockpit, but you do need a solid basic setup.

• A supported simulator: Microsoft Flight Simulator, X-Plane or Prepar3D – which version each client supports is listed on the networks’ websites.
• An account: Registration is free. Both networks provide newcomers with introductory and training material; on IVAO, you automatically receive the entry rating FS1 when you register.
• The right client: on VATSIM vPilot (Microsoft simulators, Prepar3D), xPilot (X-Plane) or swift (several platforms), on IVAO Altitude.
• A headset with a microphone: Text chat works too, but it’s more work for controllers. Voice is the standard.
• Charts and weather: Real approach charts, current weather and a flight plan are part of it. VATSIM requires that you use realistic wind, pressure and temperature values.

You’ll find hardware ideas from joysticks to throttles in the article Flight simulator hardware as a gift.

Your first flight step by step

The process is very similar on both networks. For your first flight, plan a short domestic leg between two airports with controllers rather than a long-haul flight.

Radiotelephony: the biggest hurdle

Most beginners fear the radio more than the flying. The good news: The standard phrases repeat, and controllers on both networks are used to newcomers. With three basics, you’re well prepared:

• The radiotelephony phraseology with its fixed wording for clearances, taxi instructions and altitude changes.
• The ICAO spelling alphabet and the pronunciation of numbers – without “Delta Lima Hotel” you won’t get far.
• The difference between callsign and flight number, because online you check in with the ICAO callsign of your virtual airline.

In Germany, both English and German are used on the real radio; what is common when is covered in the article English or German on aviation radio. Listening in on real radio traffic is excellent training, too – Listening to aviation radio online and Listening to air traffic radio: the legal situation describe the options and limits.

The rules in the shared airspace

A network with thousands of participants only works if everyone follows the same rules. VATSIM’s code of conduct is quite specific, and IVAO has comparable rules:

• Don’t connect on a runway or taxiway. Anyone who shows up in the middle of the runway blocks traffic.
• Don’t fly unattended. If you need to be away for a while, disconnect. Short breaks under controller control only with permission; overall, a connection on VATSIM may not remain unattended for more than 30 minutes.
• Pause only with consent. You may pause the simulator only if the controller explicitly allows it.
• Follow instructions. Heading, altitude, speed, holding pattern – you carry out basic instructions promptly.
• Don’t force priority. No flight may give itself priority. Emergencies are declared only under controller control and ended immediately at the controller’s request.
• Use the transponder correctly. An assigned code stays set until the controller says otherwise. What the emergency codes mean is shown in the article on squawk 7500, 7600 and 7700.
• Realistic names and aircraft. You connect with your real name or member number; fictional aircraft types are not allowed.

Events and community

What makes the networks lively are the events. On VATSIM, Cross the Pond is the best-known date: twice a year, thousands fly between Europe and North America, alternating westbound and eastbound, with controllers staffed on both sides of the Atlantic. Worldflight is a charity round-the-world flight. On IVAO, “Crowded Skies” is among the biggest events. On top of that come countless regional events, such as packed evenings at big German hubs like Frankfurt Airport or Munich Airport.

Exchange happens mostly through the forums, TeamSpeak and Discord of the regional units. If you want to know in general how aviation Discords work, read Discord for plane spotters; the path into the local spotter scene is described in Finding your crowd.

From virtual controller to a real career

Many members eventually switch sides and learn how controllers think. The training is graded: on VATSIM, it starts at S1 for Delivery and Ground, leads through Tower and Approach up to C1 for en route control. On IVAO, the stages are called ADC (aerodrome control), APC (approach control) and ACC (area control). Along the way, you learn a lot that you also need in reality: airspace classes, SIDs and STARs, separation and weather interpretation with METAR and TAF.

It’s no substitute for real training – the networks’ ratings have no official validity whatsoever. But if you’re toying with the idea of becoming an air traffic controller or becoming a pilot, you get a realistic feel online for how radio, planning and teamwork fit together.

Why flying online makes you a better spotter

For plane spotters, the virtual airspace has a tangible benefit. If you’ve flown dozens of approaches over the runways in Frankfurt yourself, you understand much faster at the fence why landings are happening on the other side today. The logic behind wind and runway selection is explained in the guide Understanding the runway direction in use at airports – online, you experience it live.

The training also helps when listening in on real frequencies: clearances, handoffs and approach procedures no longer sound like secret language but like a sequence you know. At spots like the Zeppelinheim viewing platform or the Munich Airport visitors’ hill (Besucherhügel), you can then tell which phase of the approach the aircraft is currently in.

What to keep in mind

• Start small. Short legs, familiar aircraft, quiet airports. The network isn’t going anywhere.
• Be honest. Tell the controller you’re new. Almost all of them adapt and speak more slowly.
• Use current charts. Outdated procedures lead to misunderstandings, especially with departure routes.
• Official software only. Download clients exclusively from the networks’ websites.
• Stay fair. Behind every radar screen sits a volunteer in their free time. Patience and a “thank you” on the frequency are good manners.

Conclusion

VATSIM and IVAO turn the flight simulator into a shared experience: real radio, real people as controllers, real procedures – and all of it free. The differences are in the details, in software, rating levels and regional activity. When in doubt, try both and stay where more is going on in your favorite airspace. Anyone who embraces the rules and practices radiotelephony takes a lot of knowledge from the virtual cockpit to the fence.