[subhro]

> That is to say, at a given speed a heavier airplane will fall out of the air [hyperbole, it will merely stall - significantly reduced lift] before it can rip the wings/elevator off [hyperbole - damage the airframe]

Turbulence, especially generated by thunderstorms, or close to it.

[vdqtp3]

Maneuvering speed is Va which is about max deflection on a single control surface, I think you're thinking of Vno if you're referring to turbulence

[subhro]

Indeed I was thinking of Vno. I just had a brain fart when I said manoeuvering speed. I meant to say maximum structural cruising speed.