How does true altitude differ from pressure altitude?

True altitude refers to the actual height of an aircraft above sea level, which is determined by considering the physical characteristics of the atmosphere at a given location. It is influenced by various factors such as temperature, humidity, and overall atmospheric pressure variations. True altitude is crucial for safe vertical separation from terrain and other aircraft, as it gives an accurate assessment of an aircraft's height relative to sea level.

In contrast, pressure altitude is a standard measure used primarily for aircraft operations and is derived from the altimeter setting based on standard atmospheric pressure (29.92 inHg or 1013.25 hPa) irrespective of the actual atmospheric conditions. Pressure altitude is primarily useful for ensuring that aircraft are flying at a consistent level relative to a standard atmosphere, which is critical during certain phases of flight, especially in situations like cross-country flying and airspace management.

The statement indicating that true altitude accounts for actual atmospheric conditions highlights why true altitude is more reflective of an aircraft's real height in the atmosphere. This differentiation is important for pilots in maintaining safe navigation and avoiding obstacles.