Beardy : I'm with Manama on this. Flown over many in the Asia area. Admit to have struggled with Met Theory in the days when the UK ATPL was VERY hard, but I thought these were 'surface' phenomina. I took that to mean I could whiz over the top. If engine failures etc worry you, when avoiding these rotters by some twenty to thirty miles and you get your feared failure...................er, where are you gonna go.............?