Density altitude is the same as the true altitude in which scenario?

• A. 4°C at 5,500 ft PA
• B. 15°C at 7,000 ft PA
• C. -18°C at 9,000 ft PA
• D. -9°C at 3,000 ft PA

Answer: (A)

Density altitude tells you the altitude in the standard atmosphere at which the air density would be the same as what you’re experiencing. It matches your true altitude when the air temperature at that height is the standard ISA temperature for that altitude, because then the air density is exactly the standard value for that level.

At 5,500 ft pressure altitude, the ISA temperature is about 4°C. That means the atmosphere is in standard conditions at that height, so the density altitude equals the pressure altitude. Under ISA, pressure altitude and true altitude line up, so the density altitude also matches the true altitude.

The other scenarios have temperatures that differ from ISA at those heights, so the density differs from the standard value and the density altitude would not equal the true altitude.