What Is ACARS in Flight Simulation?

If you've joined a virtual airline (VA), one of the first things you'll be asked to install is an ACARS client. It's the piece of software that turns a flight in your simulator into a logged flight on your airline's website, with times, fuel, a landing rate and a map of where you went.

The Real ACARS vs Flight Sim ACARS

The name comes from real aviation. The Aircraft Communications Addressing and Reporting System is a datalink that real airliners have used since the late 1970s to send short text messages between the aircraft and the airline's operations centre, over VHF radio and satellite. Among other things, it reports the four OOOI times automatically (gate out, wheels off, wheels on, gate in), which is where airlines get their block and flight times.

Flight sim ACARS is a different thing that does a similar job. Nothing is transmitted over a radio, and no real airline or aviation network is involved. It's an ordinary program on your computer that reads data from the simulator and sends it to your VA over the internet.

Some add-on aircraft also simulate the cockpit side of real ACARS (the screen where pilots request weather or receive messages). That's a separate feature of the aircraft and isn't what a VA means when it asks you to "fly with ACARS".

What a Flight Sim ACARS Client Actually Does

A sim ACARS client sits between the simulator and your airline. While you fly, it does four main jobs.

It reads the simulator

The client connects to the simulator's own data interface and reads values like latitude, longitude, altitude, ground speed, vertical speed, fuel on board, engine state and whether the aircraft is on the ground. In Microsoft Flight Simulator (MSFS) that interface is SimConnect. In X-Plane it's datarefs. The details differ per sim, and we cover them in ACARS for MSFS and ACARS for X-Plane.

It works out what you're doing

From that raw data, the client decides which phase of flight you're in: boarding, taxi, takeoff, climb, cruise, descent, approach, landing and so on. Phase detection is what lets it note your takeoff time, your landing time and when you parked, without you pressing anything. See phases of flight for what each one means.

It reports your position

At a set interval, the client sends a position report to your VA. That feeds the live map on the airline's website, so other pilots and staff can see who's flying where. Flight sim flight tracking explains how that works.

It files the PIREP

When you arrive, the client bundles everything into a pilot report, or PIREP: departure and arrival, flight time, fuel used, landing rate, the route you flew and a log of events. That's the record your airline reviews and credits to your hours. What is a PIREP goes into this in detail.

Why Virtual Airlines Use ACARS

Without ACARS, a VA has to trust whatever a pilot types into a form. With it, the flight is recorded from the simulator itself, which gives the airline:

• Proof the flight happened. A recorded track from gate to gate is hard to fake and easy to check.
• Consistent numbers. Every pilot's flight time and fuel are measured the same way.
• Rules it can enforce. A VA can set limits on landing rate, overspeed below 10,000 ft or using slew mode, and the ACARS log is how staff check them.
• Something to show off. Live maps, landing leaderboards and flight statistics all come from ACARS data.

For pilots, the benefit is less admin. You fly, and the paperwork files itself.

What You Need to Use ACARS

The setup comes down to four things:

1. A VA account. You sign up on the airline's website first, and some airlines approve new pilots by hand before you can fly.
2. The airline's chosen client. Each VA supports specific ACARS software, because the client has to talk to the airline's backend. Check the airline's pilot guide or welcome email.
3. A supported simulator on a computer. The client runs on the same machine as the sim, or on another computer on your home network if the client supports remote connections.
4. A booked flight. Your VA may want you to book or bid on a flight on its website first, so the client knows your route, aircraft and flight number.

Then you load into the sim at the departure gate, start tracking in the client, and fly.

Misconceptions About Sim ACARS

"ACARS is a plugin inside the sim." Not necessarily. A sim ACARS client can be a standalone desktop app that connects to the simulator from outside, so you don't install anything into the aircraft.

"ACARS is the same as an online ATC network." No. ATC networks give you live controllers and other traffic. ACARS records the flight for your VA. You can use both at once, and your VA may encourage it.

"Any ACARS client works with any airline." It doesn't. The client must be able to talk to your airline's system, so use the one your VA lists.

"ACARS rates my flying." It records it. Whether a landing or a flight passes is down to your airline's rules, which staff set and apply.

Frequently Asked Questions

Is flight sim ACARS free?

That depends on the client your VA uses. Some are free for pilots, and with others the airline covers the cost. Your VA will tell you what to download.

Do I need ACARS to fly for a virtual airline?

Check your VA's rules. ACARS is how a VA verifies flights, so expect to use it for normal schedule flying, though some VAs accept manual reports for certain flight types.

Does ACARS work with an online ATC network?

Yes. ACARS and an ATC network connect to the simulator independently, so you can run both on the same flight. Your VA may expect your callsign on the network to match your booked flight.

What happens if my sim crashes mid-flight?

It depends on the client. Some can recover the flight when you reload, as long as you return the aircraft to where tracking stopped. Others lose the flight and you'll need to fly it again or ask staff for help.

Can I use ACARS on a Mac?

Yes, if your simulator and your airline's client both run on macOS. X-Plane runs natively on macOS, and some ACARS clients do too.

Where Stratos Fits

Stratos is a free ACARS and telemetry client for virtual airlines, made by Skyvex Software. It reads MSFS 2020 and 2024 through SimConnect and X-Plane 11 and 12 through datarefs directly (FSX and Prepar3D are supported too), detects flight phases automatically, tracks the flight continuously and files the PIREP with your airline. It runs on Windows, macOS and Linux, and pilots never pay; the getting started guide shows how to connect it to your airline.