Why do planes fly at high altitude even across the oceans, when flying at lower altitudes require covering a shorter distance?

Question

Why do planes fly at high altitude even across the oceans, when flying at lower altitudes require covering a shorter distance?

In: Engineering

Answer 1

More fuel efficient, especially if a flight can catch a “jet stream” tail wind (available from 30,000 to 40,000+ feet) , more time for pilots to react to failures and emergencies, greater distance to glide to a suitable landing spot gives more landing options in an emergency or engine failure landing, higher altitudes give greater vertical distance and altitude options for the many jets flying in the sky at the same time. (Depending on your heading a flight may be told an odd or even number of thousands of feet to fly at )