Vik's making things complicated again.....
Most people think heat-haze only exists immediately above ground, so I described it as 'airborne' with reference to that which develops way above ground level (as in 500ft in the air). Whilst the phenomenon is usually much worse the closer to the ground you get (because the ground heats up and releases energy quickly) the belief that shooting aircraft high in the air eliminates it isn't true. Sure, the chances can be improved but you'll find a lot of people who think it is only generated by the earth/ground. As Vik says it isn't generated by the ground per se but by layers of air at different temperatures. Since these layers normally have greater temperature differences close to the ground (due to the heating of the ground) that's where you tend to most often see it.
No way of eliminating it but you can reduce the risk by...
a) getting as close to your subject as you can
b) Getting significantly elevated
c) shooting early morning or late afternoon/evening
d) not using your lens at 400mm at mid-day in July on a subject two miles away!