Flight Tips

Density Altitude

An accurate rule of thumb (usually any error will be less than 300 feet) for determining the density altitude is easy to remember. For each 10-degrees Fahrenheit above standard temperature at any particular elevation, add 600 feet to the field elevation. (And, conversely for each 10-degrees F below standard temperature, subtract 600 feet.)

Standard temperature at sea level is 59-degree Fahrenheit. For elevations above sea level, subtract 3.5 degrees per thousand feet of elevation (lapse rate is 3.5deg/1000ft) from the sea level temperature of 59 degrees. For example, at Jackson, Wyoming the elevation is 6,444. Multiply 6.444 times 3.5 for 22.55. Subtract this from 59 (59-22.55) for 36.45. The standard temperature at Jackson is 36.5 degrees. If the existing temperature is 80 degrees, subtract (80-36.5 = 43.5). Divide this difference by 10 degrees (for each 10-degrees F above standard), and multiply 4.35 times 600 (600 feet per 10 degrees) equals 2,610. Add 2,610 to the field elevation (6,444) for a density altitude of 9,054. Under the existing conditions (of our example), the airplane will perform as it would on a standard day at 9,054 feet elevation.