A jet engine creates forward thrust by drawing in a large amount of air, compressing it, mixing it with fuel and igniting it, then discharging the result as a high-speed jet of gas out the back. The reaction to that rearward jet pushes the aircraft forward.

A turbofan is the most common type of jet engine on modern aircraft. A large front fan pushes much of the air around the engine core rather than through it, which makes the engine quieter and more fuel-efficient, especially at the speeds airliners cruise at.

An afterburner injects extra fuel into the hot exhaust stream behind the turbine, where it ignites and produces a large surge of additional thrust. It dramatically boosts power for take-off or supersonic flight, at the cost of very high fuel consumption.

Jet engines let aircraft fly faster and farther than propeller-driven planes. Their development over the past several decades made fast, long-range and economical air travel practical, opening the world to both business and leisure travellers.

The core of a jet engine contains a compressor, a combustion chamber and a turbine, often wrapped by a fan in a turbofan and sometimes followed by an afterburner. Keeping such engines running can be hugely expensive, as in the case of the decades-old GE J85 engine.