Planes fly high to get above the weather, and to avoid air traffic. For jet planes, certain altitudes, all quite high, afford more efficient flight conditions.
Planes can fly fifty feet off the ground if they need to. Commercial airliners fly in the stratosphere for two reasons: there's very little general aviation traffic up there (and most of the GA guys with planes who can fly that high are good pilots), and the plane is more efficient at that altitude.
troposphère
No, there is too much atmospheric drag at these heights for a satellite to maintain an orbit, but it is too high for airplanes which have 'air breathing' engines. Some high altitude planes such as the SR-71 Blackbird and U2 can fly up to 25km, but not as high as 50km which is the lower boundary for the Mesosphere. Some experimental rocket planes such as the X-15 have been able reach these heights.
stratusphere
stratosphere
Normal planes go at 40,500 feet from ground.
30000
Around 11km
They can fly but they have a high chance of getting damaged.
If they are in the air so the answer is no, because if planes fly at high altitude and at high speed. It makes it alot difficult to get planes shot down.
High-speed fighter planes have aerofoil-shaped wings.
Pressurization keeps the people alive.
M.I.A. Paper Planes Fly like paper get high like planes
Of course, planes can fly.
I said it is a Astronomer
A large jet can get over 12 Kilometers
The heights model aircraft fly is really only governed by how far their controllers can see. In theory they can fly thousand of meters high.