Simviation Forums

Okay so I've noticed throughout my whole private training that my Cessna 152 handbook refers to Pressure Altitude on the takeoff and landing performance pages...

When you take off you really want to know about Density Altitude more than Pressure Altitude (at least what I've been taught) so you'd know if you're going to get good or poor climb performance after takeoff.....

Why does the Cessna POH's use Pressure Altitude instead of Density Altitude for it's figures? Might be a dumb question but never had it answered for me.

It came across my mind the other day when looking at a cross country flight where the pressure altitude was just under 2000 feet but density altitude was about 4500...

Thanks for the help. 8-)

The take-offs and landing charts simply groups the numbers a little tidier.  Well, same goes for the cruise charts.  If you look closely, the charts all list pressure altitude, but most of these numbers are grouped into different temperature columns.  Because density altitude is pressure altitude corrected for temperature, the math is already done for you when you line the columns and rows up. 

Think of a whizwheel flight computer.  To calculate density altitude, you simply line up the pressure altitude with the temperature and you get a number.  It's the same thing on the charts, only you don't get a density altitude figure but some kind of performance figure. 

Ah you know what that makes a lot of sense now. I guess I never really thought about it being the density altitude because I just had that temperature figure.

Thanks. 8-)

And that is why they call the PPASEL a "license to learn". 

congrats, BTW!! 

[quote]And that is why they call the PPASEL a "license to learn".

Even after you get all your ratings and licenses, there is still so much more to learn!