Did you know there are more altitudes than just pressure and density? Learn about these types of altitude and more in this weeks video podcast.
Different Types of Altitude
Hey everyone! Jason Schappert of MzeroA.com here, to talk to you a little bit about different types of altitudes. This is gonna come in real handy when we’re talking about cross-country flight planning. You’re gonna need to know what is density altitude, what is pressure altitude. Have you ever heard about absolute altitude? All these terms and more we’re gonna talk about in just a second.
Let’s go ahead and get to that video.
Alright, let’s start now with the most basic one: indicated altitude, what you read right off the altimeter. The current altitude from the altimeter when it’s set to the current altimeter setting. Does it get any easier than that?
Let’s look at another one, this one is really interesting: true altitude. True altitude is the vertical distance of the airplane above sea level. it is known as the actual altitude. It’s often expressed as feet above mean sea level (MSL). Things like airport, terrain, obstacle elevations on aeronautical charts like your sectional or your TAC are all true altitudes. So that’s something that’s kinda interesting fact for the day: true altitudes are what’s shown on your sectional chart.
Another one here is absolute altitude. This one is always changing. This is the vertical distance of an airplane above the terrain or above ground level, AGL. Think of it like a laser beam that you could shoot straight down like a radar altimeter. It would just hit the ground and read right back with the altitude. As you fly over whatever mountains you pass, towers, houses, that laser beam will get shorter and longer real quick. That’s what your absolute altitude is; it’s constantly changing. The vertical distance above the terrain or above ground level.
Big one here: pressure altitude. Pressure altitude is the altitude indicated when the altimeter is set to 29.92 because that’s our standard altimeter setting. That is the altitude above the standard datum plane, which is a theoretical plane where air pressure corrected to 15 degrees Celsius equals to 29.92. Standard temperature, standard pressure, that perfect standard day.You use pressure altitude to compute density altitude, true altitude, true airspeed and a lot of other performance things for your performance chart in your pilot’s operating handbook.
Pressure altitude you can calculate in on your E6B. It’s very easy to calculate, there’s also a formula that you can use to calculate it. All of it is in this video if you view it in MzeroA.com.
Last one here is density altitude. You have to have your pressure altitude if you want to find your density altitude. Density altitude is pressure altitude correct for non-standard temperature. It doesn’t get any easier than that. The way I put it to my students is, “It’s where your airplane feels like it’s flying.” If the density altitude is 2000 feet off the ground, your airplane feels like it’s 2000 feet already just sitting on the ground. It’s pretty neat stuff and pretty important, especially flying out west where the density altitude gets so hot and when it’s so hot, the density altitude gets so high. You may not feel that you have left the ground because the airplane feels a lot higher than it really is.
For more great flight training videos, visit MzeroA.com. I have a ton of awesome stuff on there and, if you don’t learn anything today, remember a good pilot is always learning. I’ll catch you guys later.