Above field elevation, a certain altitude above that specified for the airport.
Plane hits a certain altitude, the bomb goes off.
It was designed to be put on board an aircraft and to explode when a certain altitude was reached.
"In the rocket we turn off the motors at a certain altitude," Tom said, "and keep on flying along our orbit."
Above a certain altitude, even pure oxygen wasn't enough.
They fire a red, incendiary projectile that bursts at a certain altitude.
"Once the artillery reaches a certain altitude it explodes into fragments," he said.
Coffee also grew best at a certain altitude, whereas indigo flourished almost anywhere.
It requires a large source of energy at a certain altitude to maintaining a significant hydrodynamic escape.
"I know we're supposed to fly a certain direction at a certain altitude."
