Nicely done OhNoCB, good job!
dumbatplquestions this is the easiest way to do it(OhNoCB's way).
Basically you first need to calculate the ISA temp at the specified altitude which is 5500 ft. In order to calculate that, you always need to remember two things, the temp drop of 2 degree C every 1000 ft gained, and 1mb drop every 30 ft gained for pressure(although you do not require this info for this kind of prob).
These two point are essential and you have to remember them. The other thing you need to remember for the density altitude problems is that for every degree C deviation ABOVE ISA temp, you gain 120 ft.
Once you have the ISA temp for 5500 ft, (4 degree C) you find the ISA deviation by doing 30-4 = 26 therefore ISA + 26.
Then all is left is to add the pressure altitude you are given with the ISA deviation to get the density altitude.
5500 + (26 X 120) = 8620 ft.
Last edited by gpiper; 13th April 2014 at 19:37.
Reason: Suggested by B737900er