On my last flight my audio vario suddenly started to read a consistent
300-400 fpm too high for the present conditions. I have a mechanical
vario that remained accurate and on my L-Nav screen my average fpm
sink rate was correct. Any ideas what I can check? It was really
annoying when I was sinking at a true 300 fpm on glides but my audio
was telling me I was going up 100fpm. If only it was always that way
in real life!

Thanks,
Bruno - B4