Which of the following is NOT a type of altitude?

Speed altitude is not a recognized type of altitude, making it the correct choice in this context. Understanding the other types of altitude helps clarify why they are valid terms in aviation and meteorology.

Pressure altitude refers to the height above a standard datum plane at which the atmospheric pressure is measured. It is used in various calculations relating to aircraft performance and is crucial for understanding how altitude affects density and performance parameters.

Density altitude is related to pressure altitude, but it accounts for temperature and humidity, giving a more accurate representation of an aircraft's performance in non-standard atmospheric conditions. It plays a significant role in determining the required takeoff distance, climb rate, and other performance metrics.

Indicated altitude, on the other hand, is the altitude read directly from the altimeter, which is calibrated to the standard atmospheric pressure at sea level. This is what pilots use during flight to maintain altitude and is essential for navigation and safety.

By contrast, speed altitude lacks a formal definition in aviation, which is why it is properly identified as not being a recognized type of altitude.