Why do zero gravity flights not stall? Airbus' (A300 / A310) are being used by French companies (i.e. Novespace) that offer zero G flights.

Now the airbus seems to risk a stall at a 40 degree angle of attack (i.e.Air France 447).

In a zero g flight, they climb at 45 degrees and then nose dive at the same angle. 

Why does the climb not stall the aircraft?
The aero-dynamics of a flight in reduced gravity are different than a flight operating in normal conditions. When an aircraft is experiencing zero gravity, it does not stall because the wings are not generating any lift, because the aircraft is in a state of weightlessness.

In the paper for the requirements for zero gravity flights, it is mentioned (PDF):


  ... zero G flights stalling conditions are different as compared to
  conventional flight maneuvers, because the plane is weightless and is,
  therefore, in no need of aerodynamical support. On the other hand, a
  minimum speed is required to execute the delicate control through the
  parabola. For this reason the stalling speed is taken as the minimum
  aircraft velocity required for effective control.