Density altitude can affect the way a plane flies from takeoff to landing. Use this article as your complete guide to learn how to calculate density altitude.
As a pilot, you need to know how your plane is going to act and how it’s going to fly. Otherwise, you could put yourself, your airplane, your passengers, and any other air traffic at risk. One of the biggest factors that can affect how an airplane flies is density altitude, and it’s something that must be calculated and known while flying. So how do you calculate it?
To calculate the density altitude, you need to find the pressure altitude by using the following formula: Pressure Altitude = (29.92 - Altimeter Setting) x 1000 + Field Elevation. Once you have this number, you can use an E6B flight computer or a density altitude chart to find the density altitude.
If you're a pilot or are thinking of becoming one, then you need to know about density altitude. In short, this is the atmospheric pressure that affects an airplane and can cause problems if it's not taken into consideration. In this article, we will discuss everything there is to know about density altitude, including what it is and how to calculate it. By the time you're done reading, you'll know what to do next time you get ready to fly.
SkyTough is a site that was created by pilots with a passion for all things aviation, for pilots with a passion for all things aviation like yourself. With a technical topic like this one, we performed extensive research to make sure we’re giving you all the right formulas. But when it’s something like this one that we all do as pilots commonly, it’s a pretty straightforward topic to write about!
What is Density Altitude?
Before we get into the formulas and ways to calculate density altitude, it's important that you understand what it is. After all, knowing what something is and why it's important will cause the formula to make much more sense to you and it will stick with you more. So let's start with the basics, what is density altitude?
Density altitude is basically the pressure exerted by the weight of the air on an object. It's how "heavy" or "thick" the air is and it can be affected by many different things, including temperature and humidity. When you hear pilots talk about the density of the air, they're usually referring to its altitude.
One of the best ways to understand density altitude is that it's the pressure altitude after it's been corrected by nonstandard temperatures (and other conditions). In layman's terms, it's the altitude that the airplane will feel like it's flying in, rather than the actual physical height that you're flying at above the ground (or even when you're on the ground!).
Why is Density Altitude Important?
Now that you know what density altitude is, you might be wondering why it's so important. After all, as a pilot, you need to worry about a lot of things, and adding one more thing to the list might seem like a bit much. However, density altitude is actually very important for pilots because it can have a big effect on an airplane.
The first and most obvious reason why density altitude is important is that it can affect an airplane's performance. The higher the density altitude, the less lift an airplane will generate and the longer it will take to take off. Additionally, a high air density altitude can also cause an airplane to stall at a lower speed than normal.
Another reason why density altitude is important has to do with safety. In general, the higher the density altitude, the more dangerous it is to fly. This is because a high air density altitude can cause an airplane to lose control more easily and can make it harder to recover from a stall or spin. Additionally, a high air density altitude can also make it more difficult to see and avoid other airplanes and obstacles.
Lastly, density altitude is important because it's related to temperature and altitude. As the temperature increases, the density of the air decreases. This is why it's so important to take the temperature into consideration when you're calculating the density altitude. Additionally, as the altitude increases, the density of the air also decreases. This is why it's important to take both the temperature and the altitude into consideration when you're calculating the density altitude.
How Do You Calculate Density Altitude?
Now that you know what density altitude is and why it's important, it's time to learn how to calculate it. There are two different ways that you can calculate density altitude, and we'll discuss both of them in this section. But in order to use either method, you must first find the pressure altitude.
Step 1: Find the Pressure Altitude
The pressure altitude is the altitude above the standard datum plane. In order to find the pressure altitude, you need to know the current altimeter setting and the field elevation (i.e. what your elevation is). Once you have those two things, you can use the following formula to calculate the pressure altitude:
Pressure Altitude = (29.92 - Altimeter Setting) x 1000 + Field Elevation
For example, let's say that the current altimeter setting is 29.52 and the field elevation is 4,000 feet. Using the formula above, we would calculate the pressure altitude as follows:
Pressure Altitude = (29.92 - 29.52) x 1,000 + 4,000
Pressure Altitude = .40 x 1,000 + 4,000 = 4,400 feet.
Once you come up with the pressure altitude, you can use either of the methods below to actually determine the density altitude.
Step 2: Use an E6BFlight Computer or a Density Altitude Chart
As mentioned above, there are two different ways that you can calculate density altitude.
Using an E6B Flight Computer to Find Density Altitude
The first way is to use an E6B flight computer, also known as an E-calculator. This is a handheld device that's specifically designed to help pilots calculate different aviation-related things, including density altitude. The thing about an E6B flight computer is that it's usually actually just a handheld chart with movable parts rather than an actual computer like you would normally think of.
To use an E6B flight computer to calculate density altitude, you just need to move the temperature ring to align the outside air temperature with the pressure altitude that you calculated above. Once the outside air and pressure altitude is aligned, you can simply read off the density altitude from the appropriate location on the device. Easy peasy!
Using a Density Altitude Chart to Find Density Altitude
The other way to find the density altitude is by using a density altitude chart. These charts can be found in most aviation manuals and handbooks, and they're relatively easy to use. To make it easy to see what we're talking about, check out the density altitude chart below:
Source: Cessna Flight Training
To use a density altitude chart, you just need to know the outside air temperature and the pressure altitude you calculated above. Start by going straight up from the outside air temperature until you run into the diagonal line corresponding to the pressure altitude you calculated. Then just move your finger horizontally left until you hit the y-axis and that value will be the density altitude. Pretty easy, right?
So there you have it. That's everything you need to know about density altitude and how to calculate it. Just remember that density altitude is a measure of the air density and it can be affected by things like temperature and humidity. The only math you really have to do is to calculate the pressure altitude, then it should be smooth sailing (or smooth flying).
About THE AUTHOR
After spending years watching every video I could find about flying, I finally scratched the itch and got my pilots license. Now I fly every chance I get, and share the information I learn, here.Read More About Joe Haygood