Well how will this be explained ?:
"Elevation:The vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level."
and
"Level: A generic term relating to the
vertical position of an aircraft in flight and meaning variously, height,altitude or flight level."
How can
level (
vertical position of an aircraft in flight) be on or affixed to the surface of the earth ?
