How is density altitude calculated?

The calculation of density altitude is essential for pilots to determine aircraft performance in relation to the actual atmospheric conditions. The formula for density altitude illustrates how it is affected by both pressure altitude and temperature deviations from the International Standard Atmosphere (ISA) temperature.

In this context, density altitude can be calculated by taking the pressure altitude and adding a correction based on the outside air temperature (OAT) compared to the standard temperature (ISA Temp) at that given pressure altitude. The factor of 120 is crucial here, as it represents the approximate number of feet that density altitude increases for every degree Celsius that the temperature is above the ISA temperature.

When the outside air temperature is higher than the standard temperature at that altitude, it means the air is less dense. This reduction in air density directly impacts aircraft performance, requiring pilots to understand the resulting density altitude for safe operations. Hence, by using the formula to add the correction for temperature to pressure altitude, density altitude accurately reflects the impact of the warmer conditions on aircraft performance.

Thus, the choice stating that density altitude equals pressure altitude plus 120 times the difference between the outside air temperature and the ISA temperature correctly describes this relationship and is the appropriate choice for this question.