Why can't an airplane stall at zero G? You may be surprised to find out that an airplane can stall at any attitude if the critical angle of attack is exceeded, but it cannot stall at 0 G.


This quote found in the April 2014 issue of Flying magazine, but it seems counterintuitive to me.  

Why can't an airplane stall at 0G?
At 0 G the plane does not need to generate any lift, therefore there is no critical angle past which the airfoil cannot generate the lift required.

In addition, a sustained 0 G maneuver is a parabolic arc, which means that in theory your flight path should keep your angle of attack at zero the entire time (in a theoretical, symmetrical airfoiled aicraft). You can't stall because your AoA is constantly 0 degrees and cannot exceed the critical angle.