What does the term "density altitude" refer to?

Density altitude refers to the pressure altitude corrected for non-standard temperature conditions. It is a pivotal concept in aviation because it affects an aircraft's performance. As air density decreases, which can occur in warmer temperatures or higher altitudes, the performance of the aircraft—such as lift, engine efficiency, and propeller effectiveness—will also decline.

When temperature is higher than standard at a given pressure altitude, this results in a higher density altitude that can impede an aircraft’s performance. Pilots need this information to calculate takeoff distances, climb rates, and fuel consumption accurately. Therefore, option C is the most accurate definition of density altitude as it directly connects temperature variations to aircraft performance, serving as a critical factor for safe operations in aviation.