Determine the density altitude given the following conditions: altimeter setting 29.25, runway temperature + 81°F, airport elevation 5,250 ft MSL.

To determine the density altitude, it's essential to understand the relationship between pressure altitude, temperature, and how these factors influence the overall air density.

First, start by calculating the pressure altitude using the airport elevation and the altimeter setting. The standard atmospheric pressure at sea level is 29.92 inches of mercury (inHg). The airport elevation is 5,250 feet. The given altimeter setting is 29.25 inHg.

You can find the difference from standard pressure:

29.92 inHg - 29.25 inHg = 0.67 inHg

Next, recognize that each 0.01 inHg corresponds to approximately 27 feet of altitude change. Therefore, convert the pressure setting difference to feet:

0.67 inHg × 27 feet/inHg = approximately 18 feet.

Subtract this from the airport elevation to compute the pressure altitude:

5,250 feet - 18 feet = 5,232 feet MSL as the pressure altitude.

Next, correct for temperature deviations from standard conditions. Standard temperature at sea level is 59 °F, and it decreases by about 2 °F for every 1,000 feet of altitude. At 5,250 feet, the standard temperature