In some discussions about wake turbulence, turbulence, and V(a) lately, I found Mac's 2005 discussion about V(a) and Airbus rudder failures. In it he says:"Va is a calculated airspeed based on the actual gross weight of the airplane and the wing’s response to a 50-foot per second wind gust, or movement of the elevator." I've been digging and can't find any reference to the 50 fps wind gust. All I can find on V(a) is that it is the maximum speed at which an airplane can be stalled without exceeding the safe envelope for the airplane (based on it's category). I'd appreciate any references - I'll see about writing a letter to the editor too. -Tim Metzinger