Hi,
I have executed some of the most turbulent approaches imaginable in an F27.... Leeds-B was one of the worst, with a 60kt gust on the stb rear quarter just on touch-down. A somewhat memorable night. It seemed a robust and reliable old aircraft...but. The drift-down needs careful thought, the graphs being only the first consideration. When flying in mountainous terrain in rough air, obviously energy is soaked up and the graphs are meaningless. I would council a very cautious routes, and don't be bullied into straight-lining it, just because an ancient graph says it's OK