Learn how to change the aircraft in an FSX mission during play or permanently, with the correct .FLT edit and fixes for common mission errors.
Yes. In FSX and FSX: Steam Edition, you can usually change the player aircraft after a mission starts through Aircraft > Select Aircraft. To make the swap permanent, edit the mission's .FLT file so [Sim.0] names the replacement aircraft. Some mission triggers, checkpoints or starting positions may not suit a different type.
How do I change aircraft while an FSX mission is running?
The quickest method is to start the mission and use FSX's normal aircraft-selection menu.
- Start the mission and wait until the aircraft has loaded completely.
- Pause FSX, especially if the mission begins airborne or on a confined parking stand.
- Open the menu bar by pressing Alt if it is hidden.
- Select Aircraft > Select Aircraft, choose the replacement and confirm the change.
- Check the aircraft state before continuing. Verify the engines, landing gear, flaps, trim and autopilot rather than assuming every setting transferred.
FSX places the replacement at the player's existing position, but a larger aircraft can intersect a building, sit badly on a short runway or load with unsuitable systems. Our full procedure for switching aircraft during a flight covers the standard selector in more detail.
If Select Aircraft is unavailable or the mission restores its original aeroplane, use the permanent method below. The mission or its saved-flight configuration may restrict an in-flight swap.
How do I permanently change a mission's default aircraft?
A mission's starting player aircraft is normally identified in the accompanying .FLT flight file.
- Close FSX before editing the mission.
- Find the mission folder. Stock missions are normally under
<FSX installation>\Missions\; FSX: Steam Edition normally uses<Steam library>\steamapps\common\FSX\Missions\. - Back up the entire mission folder, not just one file. This gives you an easy way to restore the original aircraft and mission logic.
- Confirm that the replacement works in FSX. If an add-on is absent from the selector, correct it using our FSX aircraft installation steps before modifying the mission.
- Copy the exact aircraft title from the intended
[fltsim.x]section of itsaircraft.cfg. Thetitle=value matters; the folder name, manufacturer and menu description are not substitutes. See our explanation of locating and safely reading aircraft.cfg if necessary. - Open the mission's .FLT file in a plain-text editor. Find
[Sim.0]and replace the value afterSim=with the exact copied title. - Preserve the file extension when saving, then launch the mission from the beginning rather than resuming an old checkpoint.
Do not perform a global replacement in the mission's XML file. That file can contain AI objects, triggers and object references unrelated to the player aircraft. If the folder contains several flight files, identify the one associated with the mission rather than assuming every .FLT should be changed.
Why does the FSX mission stop working after the change?
An aircraft swap can fail because FSX cannot resolve the aircraft title or because the mission was designed around capabilities specific to the original model.
| Symptom | Likely cause and fix |
|---|---|
| “Aircraft not defined” appears | The Sim= entry does not exactly match an installed title= value. Check spelling, spaces and the selected livery. Follow our guide to resolving the Aircraft not defined error if the title appears correct. |
| The original aircraft returns | FSX may be loading a checkpoint or saved mission state containing the old aircraft. Restart from the mission menu and confirm that you edited the active mission copy. |
| An objective never advances | The mission may expect a particular speed range, engine configuration, switch, payload state or aircraft capability. Choose a closer substitute or restore the original. |
| The aircraft starts underground or inside scenery | The replacement has different dimensions, contact points or landing-gear height. Use an aircraft of similar size or retain the original starting model. |
| Controls or systems begin in the wrong state | Panel, engine and autopilot states do not always translate between unrelated models. Configure the replacement manually or use a more compatible aircraft. |
Which replacement aircraft is most likely to work?
An aircraft with a similar role, size and performance gives the mission the best chance of remaining playable.
- Match the original's broad category, such as piston single, helicopter, turboprop or jet.
- Choose similar take-off, climb and approach performance.
- Check that it fits the starting runway, helipad or parking position.
- Use a model that provides any radios, flaps, retractable gear or other controls mentioned in the mission instructions.
- Keep the original mission folder available if scoring, rewards or scripted sequences matter.
Changing the player aircraft does not automatically change the briefing, spoken instructions, mission scoring or AI traffic. AI and static aircraft are normally mission objects defined separately in the XML, so replacing those requires mission-authoring work rather than a simple Sim= edit.