Commercial jets can certainly fly above or below the troposphere, but this layer of the atmosphere offers ideal flying conditions for several reasons. ... In the troposphere, however, the air is thinner, thereby making commercial flights more fuel efficient.

Why do planes fly above tropopause?

Passengers planes mostly fly in the lower stratosphere layer and also in the top level of tropopause because these are less turbulent layers and provide a smoother ride. The layer that exists between the troposphere and the stratosphere is termed as the tropopause.

Do planes fly in troposphere or stratosphere?

Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below. The stratosphere is very dry; air there contains little water vapor. Because of this, few clouds are found in this layer; almost all clouds occur in the lower, more humid troposphere.