Learn what an aircraft afterburner does, how it creates extra jet thrust, when pilots use it, and why fuel and heat penalties limit its use.
An aircraft afterburner, called reheat in British terminology, is a thrust-augmentation system fitted to some jet engines. It sprays extra fuel into the hot exhaust behind the turbine and burns it, sharply increasing thrust. Pilots use it mainly for take-off, rapid acceleration, supersonic flight and combat, usually for short periods because fuel consumption is extreme.
In our Aviation & Real-World Flying coverage, we use afterburner to mean the complete augmentation system, not merely the bright flame visible behind an aircraft. It is normally found on military turbojets and low-bypass turbofans rather than high-bypass airliner engines.
How does an aircraft afterburner work?
An afterburner creates extra thrust by burning fuel in the exhaust stream downstream of the turbine.
A jet engine normally runs with surplus oxygen in its exhaust because combustion temperature must remain within the engine's limits. Fuel spray bars inject additional fuel into that oxygen-rich flow, while flameholders stabilise combustion in the fast-moving gas. Readers unfamiliar with the core cycle can review our explanation of compression, combustion, turbine drive and jet exhaust.
The extra heat expands and accelerates the exhaust, producing more thrust without sending the added combustion energy through the turbine. A variable-area exhaust nozzle usually opens when reheat is selected; without the correct nozzle response, exhaust back-pressure could disrupt the engine and cause compressor instability.
The thrust increase depends on the engine and afterburner stage. It is substantial, but it comes with a disproportionately large fuel penalty. The coloured plume is only a visible consequence: afterburner can be difficult to see in daylight, and shock diamonds may also appear in a dry, non-afterburning supersonic exhaust.
When do pilots use afterburner?
Pilots select afterburner when maximum thrust matters more than fuel economy, range, noise or infrared signature.
- Take-off or carrier launch: when aircraft weight, runway length, temperature, obstacles or the approved procedure require maximum acceleration.
- Transonic acceleration: to push through the steep rise in drag near Mach 1.
- Supersonic flight: to reach or maintain supersonic speed in aircraft that cannot supercruise under the prevailing conditions.
- Combat and interception: for rapid climbs, missile evasion, closing on a target or recovering energy after a manoeuvre.
Selection is commonly made by moving the throttles through a detent beyond maximum dry thrust. Some engines provide several afterburner zones, allowing the pilot to select less than maximum reheat.
| Power setting | Meaning | Typical purpose |
|---|---|---|
| Partial power | No afterburner | Cruise, descent and economical operation |
| Maximum dry or MIL power | Highest thrust without afterburner | Climb, take-off when sufficient and fuel-conscious combat |
| Afterburner or reheat | Additional downstream combustion | Maximum acceleration, climb or supersonic performance |
MIL power usually means maximum non-afterburning thrust, not maximum possible thrust. Terminology, detents and permitted uses vary by aircraft, so the flight manual and operating procedure always take precedence.
Why isn't afterburner used continuously?
Afterburner is not used continuously because its fuel, thermal, noise and tactical penalties quickly outweigh the extra thrust.
- Fuel and range: reheat adds a large fuel flow after the core engine is already operating at high power, rapidly reducing endurance and combat radius.
- Heat: the augmentor and exhaust nozzle must withstand very high temperatures, and some installations impose operating-time or temperature limits.
- Noise: afterburning engines are exceptionally loud, which can restrict their use near populated areas or under local procedures.
- Visibility: the hot plume raises the aircraft's infrared signature and may produce a conspicuous flame, especially at night.
Afterburner is a designed operating mode, not inherently engine abuse. Some aircraft have strict time limits; others may remain in reheat while fuel and operating conditions permit. There is no universal five-minute limit.
Does afterburner always make an aircraft supersonic?
Afterburner does not guarantee supersonic flight because speed still depends on drag, altitude, weight, inlet performance and the aircraft's structural and operating limits.
Some aircraft can exceed Mach 1 without reheat, a capability called supercruise. Conversely, an afterburning aircraft may remain subsonic at low altitude because dense air creates much greater drag. Not every military jet has an afterburner, and it cannot be added safely to an engine that was not designed for it.
Do passenger aircraft have afterburners?
Modern passenger airliners do not use afterburners because the fuel consumption and noise are incompatible with economical airline service. Concorde was a notable exception: its Olympus engines used reheat for take-off and transonic acceleration, then cruised supersonically without it.
How do flight simulators model afterburners?
A complete flight-simulator implementation changes thrust and fuel flow as well as the flame, nozzle animation and sound. A visual effect by itself does not make the simulated aircraft accelerate faster.
For older platforms, our FSX walkthrough for adding and adjusting an afterburner covers the effect setup. If reheat activates too early or never engages, check the aircraft-specific throttle mapping, axis calibration and hardware detent before altering the visual effect or flight model.