Why do passenger planes fly so high?
It may not help with a fear of heights, but soaring above the clouds makes for a smoother and more efficient journey.
Asked by: Katie Barker, Leamington Spa
There are lots of benefits to flying at an altitude of 11km. The air is thinner, producing less aerodynamic drag and thus reducing fuel consumption. It is also cold, around -55°C, which boosts the efficiency of the jet engines.
Plus, this part of the atmosphere – known as the stratosphere – is less turbulent, making for a smoother flight.
Robert is a science writer and visiting professor of science at Aston University.