Use F4 and Shift+F4 to activate afterburners in FSX, troubleshoot missing thrust or effects, and understand different MSFS and F/A-18 controls.
In FSX and FSX: Steam Edition, load an afterburner-equipped jet, set full throttle with F4, then press Shift+F4 to toggle afterburner or reheat. Press Shift+F4 again to switch it off. If nothing happens, the aircraft probably uses automatic or custom controls, lacks afterburner modelling, or has a conflicting key assignment.
FSX afterburner key: is it F4 or Shift+F4?
F4 commands full throttle in the standard FSX keyboard layout; Shift+F4 is the separate afterburner toggle.
- Load a compatible aircraft. A useful test aircraft is the Microsoft F/A-18 supplied with FSX Acceleration, FSX Gold and FSX: Steam Edition. The original boxed Standard and Deluxe editions do not include that Hornet unless Acceleration was installed separately. If you need another suitable aircraft, see our guidance on finding and correctly installing FSX fighter add-ons.
- Set full throttle. With the engines running, press
F4. A hardware throttle must be calibrated to reach its maximum output; its physical detent alone does not send an afterburner command. - Toggle the afterburner. Press
Shift+F4once. Aircraft using FSX’s standard event should engage reheat at the required throttle setting. - Confirm that it engaged. Look for stronger acceleration or increased fuel flow, supported by any exhaust flame, nozzle animation, cockpit indication or sound included with that aircraft.
- Disengage it. Press
Shift+F4again and reduce the throttle. Some aircraft extinguish the flame when the throttle is pulled back, but toggling the command off avoids leaving the system armed.
Why does Shift+F4 not activate the afterburner?
Shift+F4 fails when the input never reaches FSX, the aircraft does not support the standard command, or only part of its afterburner implementation is installed.
| Symptom | Likely cause | What to do |
|---|---|---|
| Neither thrust nor flame changes | The aircraft has no afterburner support or uses custom gauge logic | Test the same command with the FSX Acceleration F/A-18. If it works there, consult the add-on’s cockpit instructions. |
F4 works but Shift+F4 does not | The afterburner assignment was changed, removed or intercepted | Check FSX’s Buttons/Keys assignments and reassign the afterburner event. On a laptop, the keyboard may also require its Fn modifier. |
| Keyboard control works but the hardware throttle does not | The throttle axis stops below the required maximum or detent threshold | Recalibrate the axis and verify that the virtual cockpit throttle reaches its full forward position. |
| A flame appears but performance does not change | The add-on provides a visual-only exhaust effect | The aircraft also needs engine and gauge configuration that produces additional thrust and fuel consumption. |
| Thrust increases but no flame appears | An effects file is missing, incorrectly installed or not attached to the model | Check the add-on installation and FSX visual-effects setting. Reinstall any supplied effects files in the correct FSX location. |
| The command works in the F/A-18 but not an add-on | The add-on bypasses FSX’s standard event | Use its cockpit switch, automatic throttle threshold or documented custom shortcut instead. |
The stock-aircraft test is the quickest way to isolate the fault. If Shift+F4 fails in the Acceleration F/A-18 too, investigate the global control assignment or keyboard. If it fails only in one downloaded aircraft, the problem belongs to that aircraft’s configuration or control logic; our checks for FSX add-on shortcut conflicts cover that distinction.
Can I assign the FSX afterburner to a joystick?
Yes. In FSX’s control assignments, select the joystick or throttle and assign the afterburner event to a button, then test it with a known compatible aircraft.
A momentary button is usually the right choice for a toggle command. A maintained switch can send repeated inputs or leave its physical position out of step with the simulated state. Add-ons that interpret the throttle axis themselves may require an axis range beyond a detent instead of a button.
What if I cannot find the afterburner command?
Look through the complete FSX Buttons/Keys assignment list for an afterburner event, and confirm that you are editing the intended keyboard or controller profile.
If the standard event exists but one aircraft ignores it, stop changing global bindings and check that aircraft’s documentation. If there is no afterburner implementation in the aircraft at all, assigning another key cannot create one.
Does every FSX fighter jet have working afterburners?
No. A fighter model can have an afterburner-shaped exhaust without modelling genuine additional thrust.
A complete FSX implementation can contain several independent parts:
- Control logic that decides when reheat engages.
- Engine configuration that adds thrust and fuel consumption.
- Effects files that draw the exhaust flame or plume.
- Sounds and animations for the nozzles, cockpit indications and engine note.
This separation explains why one aircraft shows a bright flame without accelerating faster, while another gains performance with no visible plume. Our explanation of how real afterburners and simulated thrust effects differ covers the underlying system.
If the aircraft has no support, back up its folder before following our FSX procedure for adding afterburner configuration and effects. Editing only the visual effect will not necessarily add useful thrust.
How can I tell whether the afterburner is active?
A properly modelled afterburner produces additional thrust and higher fuel consumption; flames, nozzle movement and a louder exhaust are supporting cues rather than proof by themselves.
Compare acceleration or fuel flow under similar conditions, and watch the virtual throttle or cockpit indication if the aircraft provides one. Missing flame graphics may indicate an effects problem, while flame with unchanged performance usually means the effect is cosmetic.
What is the afterburner key in Microsoft Flight Simulator 2020 and 2024?
Microsoft Flight Simulator 2020 and 2024 do not have one reliable afterburner instruction for every aircraft and control profile, so the FSX Shift+F4 advice should not be assumed to carry over.
- Open the controls screen and select the keyboard, joystick or throttle profile you actually use.
- Search for afterburner. If
Toggle Afterburneror a similarly named action is available, assign it to a button or key and save the profile. - Advance the throttle fully. Aircraft designed around a military-power detent may require the throttle to move beyond that detent before reheat engages.
- Check the aircraft-specific controls. Some add-ons use their own cockpit switch, tablet setting or throttle logic and ignore the simulator’s generic command.
F4 is fundamentally a full-throttle command. It may appear to be an afterburner key in an aircraft that lights reheat automatically at maximum throttle, but it will not replace a separate afterburner enable command where one is required.
For the MSFS F/A-18E, verify that the virtual throttles move beyond military power into the afterburner range. If a hardware throttle stops at the detent, adjust its calibration or bind the available afterburner action rather than repeatedly pressing F4.
Is an aircraft afterburner the same as nitrous?
No. An afterburner injects extra fuel into a jet engine’s hot exhaust downstream of the turbine; nitrous oxide or “nitrous” is a different engine-boosting method.
FSX therefore has no universal nitrous button for ordinary aircraft. The relevant fighter-jet terms are afterburner and reheat, and the aircraft must be designed or modified to support them.