Module 2: The Operating Environment and Aircraft Performance

In the world of aviation, there are limitless environmental concerns that a pilot should be weary of when operating an aircraft.  One of these concerns includes density altitude. According to the Federal Aviation Administration (FAA) (2019), density altitude is “the pressure altitude corrected for temperature.” Basically, depending on the conditions of the atmosphere, the aircraft can be flying at a different altitude than what is depicted on the altimeter. Density altitude can negatively impact a pilot’s decision making and the performance of the aircraft that they operate if not taken into proper consideration.


Key factors that play into density altitude are altitude, temperature, and humidity. There’s a term in the aviation world called the three H’s of density altitude to help remember the key factors. The three H’s of density altitude are “High, Hot, and Heavy.” (Reynolds, 2012)  Some consequences of density consist of longer takeoff/landing distances, slower climb right, and declined engine performance just to name a few. (Brotak, 2013)  The increase in air temperature causes air molecules to increase in speed and expand, ultimately resulting in the air to be less dense. As the air becomes less dense, the aircraft performance begins to degrade. Aircraft will need more speed to gain the required lift necessary to takeoff and sustain flight. In worst case scenarios, an aircraft could climb at such a slow rate that they collide with surrounding terrain.

There are ways for a pilot to properly prepare themselves prior to a flight to avoid the negative impacts of density altitude. Flying in the evening or early morning will help the pilot with taking off/landing. (Aircraft Owners and Pilots Association, n.d.)  Flying at these times will help avoid the mid-day high temperatures that will decrease the air density. Pilots can coordinate with the local instructors to discuss the local density altitude procedures. (Aircraft Owners and Pilots Association, n.d.)  Decreasing aircraft weight can improve the performance of the aircraft on a high density altitude day. Ways to decrease weight include limiting supplies and luggage, and flying with less fuel in the tank. (Aircraft Owners and Pilots Association, n.d.)  Have 80% of aircrafts takeoff speed by the runways halfway point or abort takeoff. (Aircraft Owners and Pilots Association, n.d.)  With the air being less dense, the aircraft needs more time to speed up to takeoff. If the pilot does not take this into consideration, the aircraft could go off the end of the runway. Knowing what to do in a high density altitude environment is detrimental to the safety of the pilot and all passengers on board.  

 

Here is a video that demonstrates the effects that density altitude can have on an aircraft during takeoff.

 

References 

Aircraft Owners and Pilots Association. (n.d.). Density Altitude. Retrieved from AOPA: https://www.aopa.org/training-and-safety/active-pilots/safety-and-technique/weather/density-altitude

Brotak, E. (2013, November 1). Into Thin Air. Retrieved from Flight Saftey foundation: https://flightsafety.org/asw-article/into-thin-air/

Reynolds, J. (2012, July). The Front. Retrieved from NOAA's National Weather Service: https://www.weather.gov/media/publications/front/12jul-front.pdf

The Federal Aviation Administration. (2019, February 15). Fly Safe: Prevent Loss of Control Accidents. Retrieved from Federal Aviation Administration: https://www.faa.gov/news/updates/?newsid=93049