Which statement best defines pressure altitude and density altitude?

Which statement best defines pressure altitude and density altitude?

• A. Pressure altitude is the altitude in the standard atmosphere corresponding to a specific pressure; density altitude is the altitude in the standard atmosphere corresponding to the current air density.
• B. They are the same thing.
• C. Pressure altitude is based on humidity.
• D. Density altitude equals actual height above sea level.

Answer: (A)

In aviation, pressure altitude and density altitude describe how the atmosphere affects the reference height you read or use for performance, but they measure different things. Pressure altitude is the altitude in the standard atmosphere that corresponds to a given pressure. In other words, if you take the current pressure and look for where that same pressure occurs in a model atmosphere, that location’s altitude is the pressure altitude. Density altitude uses air density instead of pressure. It’s the altitude in the standard atmosphere that would have the same air density as the air you’re actually experiencing. Because density depends on temperature and humidity (and pressure), density altitude shifts with weather. Warmer or more humid air is less dense, so density altitude is higher than your true altitude; cooler, drier air makes density altitude lower. They aren’t the same thing, and humidity influences density altitude but not pressure altitude. Density altitude is not the actual height above sea level. This definition pair is the precise way to distinguish the two concepts.

In aviation, pressure altitude and density altitude describe how the atmosphere affects the reference height you read or use for performance, but they measure different things. Pressure altitude is the altitude in the standard atmosphere that corresponds to a given pressure. In other words, if you take the current pressure and look for where that same pressure occurs in a model atmosphere, that location’s altitude is the pressure altitude. Density altitude uses air density instead of pressure. It’s the altitude in the standard atmosphere that would have the same air density as the air you’re actually experiencing. Because density depends on temperature and humidity (and pressure), density altitude shifts with weather. Warmer or more humid air is less dense, so density altitude is higher than your true altitude; cooler, drier air makes density altitude lower. They aren’t the same thing, and humidity influences density altitude but not pressure altitude. Density altitude is not the actual height above sea level. This definition pair is the precise way to distinguish the two concepts.