Since we are finally experiencing some summer weather here in Cali it's time to start thinking about Denisity Altitude. These charts were produced by Flightsafety Int'l and came out of a book that I use alot when calculating performance data. It makes quick work out of a DA problem. Hopefully some of you can use these. I have them shrunk down and taped to my kneeboard.


To use this chart use your altimeter setting and come up with a plus or minus number. Then add or subtract this from you FIELD ELEVATION.



This one is pretty self explanatory just remember it uses True Temp and PA not Field Elevation.

If you're an equation type of person, this is good to memorize for a rough determination of Density Altitude, especially if you're not packing any tables or charts with you:

DA = PA + (120 Vt)

Where:

DA = density altitude
PA = pressure altitude at the level you desire density altitude
120 = a temperature constant (120 feet per 1°C)
Vt = Actual temperature minus corresponding Standard temperature at the level of the pressure altitude.

For example, let's say the surface temperature is 30°C and your pressure altitude is 4,500 feet.

Remember that the standard lapse rate is 2°C per 1000 ft. So, for 4,500 ft, the standard temperature should be 6°C.

Plug these values into the formula to find the following:

DA = PA + (120 Vt)
DA = 4,500 feet + [120(30°C - 6°C)]
DA = 4,500 + 120(24)
DA = 4,500 + 2,880
DA = 7380 feet


This same problem on the chart comes up with about 7,200 ft, so it's pretty close.