This quick slide illustrates 5 different types of altitudes and how to go from one to the other. Pressure altitude + outside air temperature are most useful when calculating aircraft performance. Remember a couple of things:
- The altimeter setting is nothing but the pressure reading at mean sea level.
- To get from indicated to pressure, either set your altimeter to 29.92 if you are in the plane or otherwise use the formula (you will need the field elevation and current altimeter setting).
- On a hotter than standard day (>15c), density altitude will exceed pressure altitude – as pressure altitude is based on standard temperature
- Indicate airspeeds remain the same regardless of density altitude because the airspeed indicator is connected to the static port and hence affected by air density.
AirSpeed Alive 