Pressure Altitude Question
I came across a question from the questions listed by previous candidates that I couldn't answer. I was wondering if anyone could lend a hand with this one:
" If we are at 3000' and the QNH is 990, what is the pressure altitude?"
From what I've read, altitude increases 27ft every 1 mb. So, would this simply be (1013.25 - 990) x 27 +3000 = QNE = 3627.73 ?
The difference between the pressure altitude and the actual altitude seems to be a little on the high side.
Thanks for help.