Hello Fly.b737
FL090 = 9000ft indicated, with 1013.25hpa in your altimeter window. Now remember the rule "from high to low(pressure) and from warm to cold(temperature) => look below"
So your pressure corrections & your temperature corrections have to be subtracted from 9000ft with a QNH 981 and an ISA -14°C atmosphere
giving 9000ft - 960ft - 448ft = 7592ft true altitude
Density altitude(used for performance calculations, wings & engines only "know" density altitudes) = pressure alt, corrected for non standard temperatures
Density alt. = press.alt 9000ft +120(delta ISA) = 9000 + 120(-14) = 9000 - 1680 = 7320ft
BM
Last edited by blackmail; 27th Aug 2018 at 20:13.
Reason: temp corrections