Density altitude is defined as the pressure altitude corrected for nonstandard temperature and is used to evaluate aircraft performance.

• A. True altitude
• B. Pressure altitude corrected for nonstandard temperature
• C. Actual altitude above mean sea level
• D. Calibrated airspeed equivalent altitude

Answer: (B)

Density altitude equals pressure altitude corrected for nonstandard temperature, and it tells you how the air density at a given altitude will affect aircraft performance. Pressure altitude is the altitude corresponding to the current pressure in a standard atmosphere; when you apply a temperature correction for nonstandard conditions, you get density altitude. Hotter air than standard makes the air less dense, so density altitude rises and performance falls (less engine power, weaker lift, and slower climbs). Cooler air makes density altitude lower and improves performance. This concept is used because performance—takeoff distance, climb rate, and power requires—varies with air density, not just with height.

True altitude and actual altitude above mean sea level describe how high you are above the Earth’s surface, not the air’s density. Calibrated airspeed equivalent altitude isn’t the term for density altitude; density altitude specifically accounts for how temperature affects air density and performance.