Pressure Altitude Flashcards
What is Pressure Altitude?
Pressure altitude tells you how high you’d have to fly in a standard atmosphere to have the same pressure as whatever the current altimeter setting is.
It is your altitude corrected for non-standard pressures only.
What are the two ways you can get the pressure altitude?
- If you are sitting in the plane, you can just set 29.92 in the kollsman window.
- 29.92 - whatever the current setting is x 1000
If we could hypothetically go below ISA sea level pressure, what would the pressure be at -1000 ISA Sea Level?
30.92
Why do we want to calculate pressure altitude?
Like density altitude it gives us a better idea of how our AC will perform because it tells us where the airplane thinks it is. Some POH charts use Pressure Altitude only, some want density altitude. Either way, you need to find pressure altitude to find Density Altitude.
If you have a local alt setting of 30.82, would your airplane think it was higher or lower than it actually is compared to ISA?
29.92
-30.82
——–
-0.9 x 1000 = -900ft
When the pressure is higher (when the number is higher/bigger) than 29.92, the answer is going to be that your airplane thinks it is lower than it actually is
If you are flying with your last altimeter setting and coming in to land at an airport with a different alt setting and you forget to reset it, what should you remember in terms of how high or low you are?
If the alt setting at your destination is higher than the one you last put in your kollsman window, your plane will think, and your altimeter will indicate, that you are lower than you are.
If the altimeter is set too low, it will read too low.
