Short instructor-led video explaining pressure altitude and density altitude for helicopter pilots. The speaker demonstrates pressure altitude using the Kollsman (barometric) window set to 29.92 and defines density altitude as pressure altitude corrected for temperature and humidity, noting its practical effect on helicopter performance (e.g., an 800 ft field with density altitude 2500 ft will degrade performance).
Questions this video answers
Set 29.92 in the Kollsman (barometric) window on the altimeter.
Density altitude is pressure altitude corrected for temperature and humidity.
The helicopter will operate as if it were at 2500 ft (reduced performance compared with 800 ft).
Chapters
Pressure altitude. Pressure altitude and density altitude are two that we screw up all the time. This is not really super hard, but then again, it's not very easy. These things can be really tough when you're thinking pressure altitude. Density altitude. What is pressure altitude? Pressure altitude is what you get when you dial 29.92 in your Colzman window. If you look at the diagram here, we went downstairs the other day, a student said, what is the Colzman window? We went downstairs, we took a photo of this and brought it upstairs so we could make sense of this. Your altimeter on the right, we put in the barometric pressure setting for the day, which is what shows the field elevation. We know that 800ft. Then in the other altimeter, we set in 29.92, and you read pressure altitude directly off that altimeter. So that is one that you're going to be asked. You have to know the difference.
To memorize. Density altitude. What is density altitude? Density altitude is pressure altitude corrected for temperature and humidity. The thing that you're going to notice is in the wintertime, you're checking weather. They don't say nothing about density altitude because in the wintertime, performance is good, the air is cool, it's not a big deal. Summertime, as the day heats up, gets more humid. You go to check your weather. You may hear, maybe like us here, we're at 800ft. You may hear density altitude, 2500. When you hear that, you know, uh, oh, that means it's going to be a bad performance day. The helicopter is going to operate like it's at 2500ft. So density altitude is pressure altitude corrected for temperature and humidity.
