Determine the density altitude given an airport elevation of 5,515 ft, OAT of 30°C, and an altimeter setting of 29.40" Hg.

• A. 8,000 feet
• B. 8,900 feet
• C. 9,100 feet
• D. 9,500 feet

Answer: (C)

To determine density altitude, we must first calculate the pressure altitude and then adjust it for the temperature. The process involves several steps.

1. Pressure Altitude: This is calculated by taking the airport elevation and correcting for the altimeter setting. The standard atmospheric pressure at sea level is 29.92 inches of mercury (Hg). The altimeter setting provided is 29.40 Hg. The difference is 0.52 inches. Each 0.01 inch of mercury change corresponds to 30 feet of altitude. Therefore, we can find the pressure altitude as follows:

[

\text{Pressure Altitude} = \text{Airport Elevation} + ((29.92 - \text{Altimeter Setting}) \times 30)

]

Plugging in the values:

[

\text{Pressure Altitude} = 5515 + ((29.92 - 29.40) \times 30)

]

[

= 5515 + (0.52 \times 30)

]

[

= 5515 + 15.6 = 5530.6 \text{ feet}

]

2