definitions
Torque margin = amount of power left (in torque terms) between max allowable and that required for the flight condition
Thrust margin = same as above but expressed in payload (lbs or kg of capacity left)
Ceiling = maximum allowable operating altitude, normally the point at which a rate of climb of 100 fpm cannot be sustained or the envelope limit if lower
reject alt = maximum distance above the ground at which you can safely land after a single powerplant failure
flyaway = technique used in hover or during low speed flight to avoid hitting the ground after a single powerplant failure.
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