If you have been in an airport once, you should have seen the aircrafts going backwards by pushback vehicles. Have you ever think about how airplanes go backwards without them? Or do they be able to go backwards?
The answer is YES! But it happens not like in cars.
Airplanes do not have traction on their gears like cars by using the engine with the transmission. They use various types of different engines which are using for producing thrust.
As intead of reverse gears, the engines have a system of Reverse Thrust. This is a system in airpanes to direct the thrust of the engines forward, instead of backward to produce opposite motion to the airplane or in braking.
Now, we are ready to mention about functions of reverse thrust.
Using while landing
A commercial airplane lands at speeds between 240–260 km/h. At this high speed, if airplane apply hydraulic braking, it will cause damage in the brakes. To stand apart from this, reverse thrust is using by airplanes which direct the thrust forward, resulting in braking.
Using on taxiways
In some airports, where the pushback vehicle in unavailable, the aircraft can reverse itself from the gate, by use of Reverse Thrust. This system is known as Powerback.
But powerback is forbidden at some of the airports today because of opening the reverse thrusters at the gate could damage the airport terminals, or can harm the ground equipments and personnel, due to the high speed JET BLAST.