So if you’re like I was, let me explain why learning in a high DA training environment is something you should take into serious consideration. It turned out that I just happened to pick a school where all my flying would be in high density altitude, and looking back on it I am so happy that I did. Honestly, I didn’t really think about DA when I chose a school. I can tell you that it didn’t mean anything to me when I first started looking into flight schools.īack then, I had seen it mentioned here and there, and roughly understood that it was supposed to make you a better pilot, but I didn’t understand why, or what high density altitude actually meant. You may have heard about “flying in High DA” or “High Density Altitude”, but does that really mean anything to the aspiring helicopter pilot looking for the right training program? And you really don't want to be caught doing this takeoff.Guidance Aviation graduate and current employee Andrew Craw. And when the weather's hot and you're at a high altitude, it can make a big difference in performance. What's It All Mean?ĭensity altitude's always a factor you should consider - no matter when you're flying. If the humidity's high, your aircraft could perform like it's several hundred feet higher. You can see that humidity doesn't have as much of an effect on density altitude as temperature and pressure do, but it's something to consider. At the average high humidity of 72%, the density altitude increases by 480 feet to 8926 feet.

Adding 22% humidity increases the density altitude by 146 feet to 8592 feet.

Lets use an average July day in Denver when the temperature's 31.1 degrees Celsius. Unfortunately, factoring humidity into density altitude is complicated, but there's a great calculator for it here. How much of an effect does humidity have?ĭuring July in Denver, the average daily low relative humidity is 22%, and the average daily high relative humidity is 72%. So, when you have more water vapor in the air, the air has less mass - which means it's less dense. And, water vapor takes up about the same amount of space. What's with all of the chemistry?!? Water vapor weighs less than the Nitrogen or Oxygen molecules that make up the rest of the air. Water molecules are made up of two Hydrogen atoms, each of which weighs one unit, and one Oxygen atom, which weighs 8 units - so a molecule of water vapor weighs 10 units. Oxygen's atomic mass is 8, so one O 2 molecule weighs 16 units. Oxygen in the atmosphere generally exists as a O 2 molecule, which means two Oxygen atoms are bound together. Since Nitrogen's atomic mass is 7, one Nitrogen molecule weighs 14 units. In the atmosphere, Nitrogen usually exists as a N 2 molecule - which means two Nitrogen atoms are bound together.

The amount of water vapor in the air varies, but it can contribute up to 1%. Humidity: The Factor You Don't Computeĭid you know that humidity also plays into density altitude? Air is made up of 78% Nitrogen, 21% Oxygen and 1% other gasses. What does that do to Denver's density altitude? On an average July day, the temperature increases Denver's density altitude by 3012 feet to 8446 feet! That's why every one of Denver International's runways is at least 12,000' long - and one is 16,000' long. On an average day in July, Denver's temperature is 27 degrees Celsius above standard! Since the standard temperature decreases 2 degrees Celsius for every 1000 feet, Denver's standard temperature is roughly 4.1 degrees Celsius. How about Denver, Colorado? Denver International Airport sits at 5434 feet, and its average temperature in July is 88 degrees Fahrenheit (31.1 degrees Celsius). How much does your density altitude increase? It increases 1535 feet - that's on an average day! Miami's essentially at sea level, so on average during July, the temperature's 13.3 degrees Celsius above standard. Imagine you're in Miami, Florida during July, where the average temperature is 83 degrees Fahrenheit (28.3 degrees Celsius). But how much of a factor does non-standard temperature play? As you climb, the temperature decreases about 2 degrees Celsius per 1000 feet. The standard temperature at sea level is 15 degrees Celsius, or 59 degrees Fahrenheit. When the air is warmer than standard, it's less dense and performance decreases.

Density altitude