How are pressure altitude and density altitude related?

Density altitude and pressure altitude are closely related because density altitude is essentially pressure altitude adjusted for variations in temperature. Pressure altitude is the altitude indicated when a pilot sets the altimeter to the standard sea-level pressure of 29.92 inches of mercury, while density altitude accounts for both pressure and temperature effects on air density.

When the temperature deviates from the standard atmosphere, the density of the air changes, which can significantly affect aircraft performance. Therefore, density altitude reflects how well the aircraft can perform in relation to the current atmospheric conditions — it provides a more accurate measure of the aircraft’s performance capabilities under those specific circumstances.

This relationship is crucial for pilots, as operating an aircraft in high density altitude conditions may reduce engine performance, lift, and climb rates, as the air is less dense. Understanding this concept helps pilots make informed decisions regarding takeoff distances, climb performance, and overall flight safety, particularly at high elevations and on hot days.