How do I change an aircraft's ATC callsign in FSX?

In FSX and FSX: Steam Edition, change an aircraft’s ATC callsign for one flight in the selected aircraft’s Details panel. To change its default, edit the correct [fltsim.x] block in aircraft.cfg: use atc_airline for the spoken operator name, atc_flight_number for the number, and atc_id for the registration.

How do I change the callsign for one FSX flight?

Use the Aircraft Details panel when you want a temporary callsign without editing configuration files.

1. Open Free Flight and select the option to change the current aircraft.
2. Highlight the aircraft variation you intend to fly, then open its Details panel.
3. Enter the tail number, choose an available airline callsign and enter the flight number.
4. Enable the Heavy option only when that suffix is appropriate for the aircraft.
5. Accept the details, select the aircraft and load the flight.

We recommend this method when you only need a callsign for the next flight. The drop-down list also shows callsigns that the installed FSX voice data can pronounce.

Treat the result as flight-specific rather than a new aircraft default. A saved flight can retain those details, while missions may carry scripted aircraft or ATC settings that override them.

How do I make an aircraft.cfg callsign permanent?

A permanent default must be entered in the selected livery’s own [fltsim.x] section inside aircraft.cfg.

1. Close FSX. This prevents the loaded aircraft state from masking the change while you work.
2. Find the correct file. It is normally inside the aircraft’s folder under SimObjects\Airplanes. Installation paths differ between boxed FSX, Steam Edition and custom Steam libraries, so use our aircraft.cfg location and safe-edit instructions if the file is missing or Windows refuses to save it.
3. Back up aircraft.cfg. Keep an unchanged copy outside the aircraft folder.
4. Identify the active variation. Match its ui_variation, texture and unique title. Do not assume that the livery you fly is always [fltsim.0].
5. Edit the ATC entries. Change the existing lines or add one instance of each required field. Avoid duplicate entries in the same section.
6. Save the original filename. It must remain plain-text aircraft.cfg, not aircraft.cfg.txt.
7. Restart FSX and test a fresh Free Flight. Select the same variation you edited rather than loading a saved flight that contains old aircraft details.

Every repaint can have different defaults, even when several liveries share one aircraft folder. Our guide to how FSX matches each fltsim section to an aircraft variation explains the relevant identity and ATC entries.

What do I put in the FSX aircraft.cfg callsign fields?

There is no single callsign= line in FSX; what you put depends on whether ATC should use an airline-and-flight-number callsign or the aircraft registration.

For an airline-style callsign, a variation could contain:

• atc_id=N123AB
• atc_airline=World Travel
• atc_flight_number=452
• atc_heavy=0

FSX will use the airline and flight number only if its voice data recognises the atc_airline value. Do not combine everything into one entry such as atc_airline=World Travel 452.

For a private or general-aviation aircraft that should be addressed by registration, set atc_id and leave atc_airline and atc_flight_number blank. The separate atc_type and atc_model settings describe the aircraft; they do not set its operator callsign.

Can I type any airline name into atc_airline?

No. FSX can speak only callsigns present in its installed voice data, so arbitrary text in atc_airline does not create a new spoken phrase.

The airline’s brand, code and radio telephony callsign may all be different. Choose a callsign offered in Aircraft Details or copy the exact value from a working aircraft entry. Capitalisation is rarely the main problem; using a phrase absent from the voice data is.

A genuinely new spoken callsign requires a compatible voice addition as well as the matching aircraft.cfg value. Our Southern callsign package and configuration example demonstrates that two-part EditVoicepack process.

Why does FSX ignore the new callsign?

Most failed callsign edits come from an unsupported voice entry, the wrong livery block, a file that was not saved correctly or flight-specific details overriding the default.

• ATC uses the registration: check that atc_airline exactly matches an installed spoken callsign.
• Nothing changes: compare title, ui_variation and texture with the aircraft variation selected in FSX. A mistake we see constantly is editing the first [fltsim.x] block rather than the active repaint.
• The file will not save: Windows may protect an FSX installation under Program Files. Also check that the editor has not added a hidden .txt extension.
• The old callsign remains: exit FSX completely and test from a new Free Flight. Aircraft Details and saved flights can preserve their own values.
• The edit later disappears: some add-on configuration utilities regenerate aircraft.cfg. Use the supplied utility for that aircraft when it controls registrations or liveries.

If the source is still unclear, follow our aircraft.cfg change troubleshooting checklist to distinguish a path, permissions, variation or cached-flight problem.

Does aircraft.cfg change my online-network callsign?

No. These settings control FSX’s built-in aircraft identity and ATC. An online network’s pilot client normally uses the callsign entered when connecting, so change it there and follow that network’s callsign rules rather than relying on aircraft.cfg.