Originally Posted by
FlightDetent
The definition of GD on the FBW Airbii is
- the optimum engine-out speed.
My guess is that applies for flight with Beta target centered.
From the FCOM (A321NEO):
Engine-out operating speed in clean configuration. (Best lift-to-drag ratio speed).
Also corresponds to the final takeoff speed. Represented by a green dot on the PFD scale. Below 20 000 ft equal to 1.5 × weight (tons) +110 Above 20 000 ft, add 1 kt per 1 000 ft