What atmoshpere layer does planes fly in?

I am confused and feel stupid for asking this but do planes fly in the Troposphere or the Stratosphere? My diagram in my science book is bad im pretty sure it is the troposphere tho.


PLZ Help!





TY!What atmoshpere layer does planes fly in?
Troposphere. It extends out to 11 km and then the other spheres begin. No commercial flights go that high; they usually fly at about 20 to 30 thousand feet. 11 klicks would be 36,000 ft.What atmoshpere layer does planes fly in?
Airplanes fly in the stratosphere routinely. Long distance airline flights exceed 36,000 feet all the time.





Many military aircraft fly in the stratosphere for extended periods of time.





Having said all that, most flying is done in the troposphere.
Airliners tend to fly in the stratosphere, because the air is less dense and very calm. That reduces turbulence and wind resistance, thus making the airplanes more efficient. They also try to find ';jet streams'; flowing in the same direction as they are flying, because the velocity of the jet stream is added to the ';ground speed'; of the airliner.
Airlines prefer to fly in the troposphere and spy planes or supersonic jets fly in the stratosphere