At that altitude, the air is very thin, and that greatly affects the lowest safe speed.
It measures air speed—not ground speed, but the speed of the airplane at altitude.
But the Inmarsat information was unable to indicate either the altitude or the speed of the airplane.
Thunderstorms at that altitude, the Times of London reports, can have the “energy of nuclear explosions.”
The airplane flew at an altitude higher than that of Mount Everest—about 38,000 feet compared to Everest at 29,000 feet.
It dropped to an altitude of only a few hundred feet and turned and went back over the ground it had just crossed.
After a while, the ship had reduced its speed and altitude to reasonable values.
The rocs had better range and altitude than any planes of equal hauling power.
They made their last camp at an altitude of eleven thousand feet.
For every 900 feet of altitude the height of the mercury is about one inch less.