By the time the vortex has sunk 1000', it really isn't a problem for a large jet. When it has happened rarely across the Atlantic or any other airway, there is just a little bouncing around with hardly any lateral motion. You just steer the autopilot a few degrees to get out of it. The core rotation has largely dissipated by the time the vortex has sunk- it's just lightly eddying air then. Remember, any more of a crosswind than a few knots will blow the vortex out of the way by the time it has sunk.