What is the definition of "density altitude"?

Density altitude is defined as the pressure altitude corrected for non-standard temperature and is a crucial factor in determining aircraft performance. When the temperature deviates from the standard atmosphere (usually defined as 15 degrees Celsius at sea level), the actual air density changes, which impacts how well an aircraft can perform during critical phases of flight such as takeoff, climb, and landing.

This adjustment is important because aircraft engines, propellers, and wings all rely on the density of air to function optimally. At higher density altitudes, the aircraft may require longer takeoff distances, have reduced climb rates, and experience lower engine performance. Therefore, correctly understanding density altitude allows pilots to make informed decisions regarding aircraft performance in varying temperatures and elevations.

The other options do not accurately reflect this key concept in aviation. The height of an aircraft above sea level pertains to geometric altitude rather than density altitude. The concept of air being less dense than sea level is vague and does not capture the necessary adjustments for non-standard temperature. Lastly, stall altitude refers to a specific aerodynamic phenomenon rather than a measurement linked to air density and aircraft performance.