Originally Posted by
dont overfil
It's not just over the mountains there can be problems.
Last year I had 800fpm down (and up) 15nm south of Newcastle. The autopilot tripped as it couldn't keep up. The wind was negligible on the ground but showing 270/40 at 8500ft. We were 40nm east of the Lake district which I presume was causing the problem.
Fortunately it only lasted a few minutes. It took full power and a speed loss of 45kts to maintain altitude.
D.O.
The Penines often generate mountain wave which can affect anywhere downwind of them, and that sounds exactly like what you were in. Not sure how good a generator the Lakeland hills are, but I expect they contributed. A good resource for predicting wave (and thermal activity) is RASP -
RASPtableGM