eckhard, one thing I haven't resolved myself adequately. Picture a jet autopilot engaged doing continual steady 360 degree turns at 200 kts. Then do it in a 200kt jetstream. The aeroplane is stationary at one point and 400 kts 180 degrees later. There are tremendous kinetic energy changes (based on the Earth's surface). Yet the aeroplane steadily and lazily continues turning. Whilst I appreciate you wouldn't expect to have full throttle into wind and idle downwind, I don't see why the fairly rapid kinetic energy changes don't affect the aeroplane in any way. Yet for a sudden wind shear, they do.