An American Airlines plane was forced to return to Las Vegas on Wednesday after reporting an engine issue shortly after ...

Because other aircraft, including different Airbus models and those of the other industry giant, Boeing, have different systems, only the Airbus A320 planes make this distinctive sound.

Once the plane has touched down on land, it sounds like the engines are revving for takeoff. This is just the captain reversing the engine thrusts to help slow the aircraft down.

Planes can make strange noises once they're in the air which can be 'scary' for nervous fliers - but one pilot has said there's nothing to worry about.