Traditionally, landing aircraft approach a runway by ‘stepping’ down from the cruising level to the ground (dark blue path). At each step, the pilots have to alter the thrust of the engines to level out the aircraft.
New technology means that airlines can work with air traffic control and airports to create a much smoother descent to the runway, cutting out the stepping procedures and cutting fuel use and noise at the same time (light blue path).
In fact, airlines estimate that each continuous descent approach can save 150kg of jet fuel (around 500kgs of CO2). Continuous descents are being implemented at hundreds of airports all over the world and the below video shows the way they work and the noise benefits: