Using the density altitude approximation density altitude ≈ pressure altitude + 120 × (OAT − ISA), what is the density altitude if the pressure altitude is 3,000 ft and the OAT is 6°C warmer than ISA?

Using the density altitude approximation density altitude ≈ pressure altitude + 120 × (OAT − ISA), what is the density altitude if the pressure altitude is 3,000 ft and the OAT is 6°C warmer than ISA?

• A. 3,720 ft
• B. 3,600 ft
• C. 3,520 ft
• D. 4,200 ft

Answer: (A)

Density altitude is the altitude that corresponds to air density, so it uses pressure altitude and then corrects for how warm or cold the air is compared to standard conditions. Warmer air is less dense, which makes the density altitude higher. Using the given approximation: density altitude ≈ pressure altitude + 120 × (OAT − ISA). Here the pressure altitude is 3,000 ft and the air is 6°C warmer than ISA, so 120 × 6 = 720 ft. Add that to 3,000 ft and you get 3,720 ft. So the density altitude is about 3,720 ft. This quick rule of thumb assumes the change in density with temperature is roughly 120 ft per degree Celsius and is handy for planning—real value can differ slightly with humidity and exact pressure, but this calc gives a solid estimate.

Density altitude is the altitude that corresponds to air density, so it uses pressure altitude and then corrects for how warm or cold the air is compared to standard conditions. Warmer air is less dense, which makes the density altitude higher.

Using the given approximation: density altitude ≈ pressure altitude + 120 × (OAT − ISA). Here the pressure altitude is 3,000 ft and the air is 6°C warmer than ISA, so 120 × 6 = 720 ft. Add that to 3,000 ft and you get 3,720 ft.

So the density altitude is about 3,720 ft. This quick rule of thumb assumes the change in density with temperature is roughly 120 ft per degree Celsius and is handy for planning—real value can differ slightly with humidity and exact pressure, but this calc gives a solid estimate.