The Operating Environment and Aircraft Performance

 Density Altitude

       An aircraft's capabilities are said to be measured in relation to the main goal for which it was built, and this is referred to as performance. However, there are several elements that normally impact an aircraft's performance. Next, we'll explore pressure altitude, a component that has an impact on how an airplane performs. 

    This is possibly one of the most crucial elements impacting how the airplane performs at high temperatures. Each altitude corresponds to a certain pressure under standard conditions. Using the pressure, we can then calculate the altitude. The same situation occurs with density altitude. Each altitude has a density corresponding with it under standard conditions.  Then we can say that "Density altitude is pressure altitude corrected for nonstandard temperature" (FAA, 2016, p. 11-3). Changes in altitude, temperature, and humidity all have an impact on the density of the air, which is why the density of the air falls as temperature rises. Additionally, as the altitude rises, both air pressure and density decrease.

    So what effect does density have on the aircraft? "The conditions that result in a high density altitude are high elevations, low atmospheric pressures, high temperatures, high humidity, or some combination of these factors. Lower elevations, high atmospheric pressure, low temperatures, and low humidity are more indicative of low density altitude" (FAA, 2016, p. 11-4). In other words, the higher the flight height, the lower the density, and consequently, the lower the lift and the lower the drag. 

    As a result, the density altitude measured is comparable to the altitude in the standard atmosphere where the air has the same density, enabling us to compute the aircraft's performance with a suitable degree of approximation and so optimise its performance. Air density is might be the single most important factor affecting aircraft performance, influencing lift, drag, engine performance, and propeller efficiency. For example, the drop in lift density must be compensated for by an increase in speed, which requires higher efficiency in the engine and propeller, both of which have decreased due to the low density, all of which reduces the airplane's performance in low-density altitudes significantly. 

    The mitigation strategy that can be employed to address this environmental factor is knowing the weather conditions, such as rain, storms, fog, wind, etc., while making flight plans. To calculate the density altitude, you must know the temperature. Our aircraft's performance degrades with every increase in density altitude.

References

 FAA. (2021). Pilot's handbook of aeronautical knowledge.                                                                   

    https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/phak/13_phak_ch11.pdf