Sometimes turbulence in the air causes the plane to rise and fall.
Your coffee or other drinks may spill onto the table in front of you.
The 'fasten seat belt' sign is switched on.
In this situation the pilot must take the plane higher.
Of course the engines work harder again.
A long way from the airport, perhaps 300 kilometres, the plane begins to descend.
the noise of the engines may sound quieter.
A very shallow angle of descend saves a lot of fuel.
A steep angle of descent may cost 360-450 litres more petrol.
In order to slow down the pilot changes the shape of the wings.
He also lowers the wheels.
Nearly on the runway, the front of the plane rises and a moment later the wheels hit the runway.
suddenly the engines make a loud noise.
As the wheels touch the runway the pilot lifts the spoilers in the wing.
And he puts the engines into reverse.