Definitely a non no. You simply can't see the display.
Well I've never had the problem with portable GPS units and polarised glasses...
wsmempson says -
The windscreen suddenly looks as if it is criss-crossed with millions of spidery, silver crazed lines - which very much spoil the view.
Incorrect, not in 99% of light aeroplanes. In our jets with heated and whatnot windshields, yes, but plain old Cessna/Piper perspex is no problem at all.
I think some people are being a little OTT about things which really are no issue at all when in the air. I have a couple of thousand hours in Cessnas - the polarised sunglasses are 400 hours TT now, and so far, I've never witnessed any of the above mentioned effects. Not saying they don't happen though...
