Runway 06R

The calculation of density height requires a few bits of information:

Elevation, QNH and Temperature.

Example

Elevation: 8000 Feet
QNH: 1032 hPa
Temperature: +21 degrees

Use the QNH to work out the pressure height

1013 – 1032 = -19
-19 x 30 = -570
-570 + 8000 = 7430

So our pressure height is 7430 feet, we then use that number to work out the ISA temperature for the given height.

ISA temperature at ground is +15 degrees, and for every 1000 feet of height we loose 2 degrees so we round off to the nearest 500 feet so for our next calculation 7430 becomes 7500. So we then do the following +15 – (2 x 7.5 = 15) = 0 degrees

So our ISA temperature for our height is 0 degrees, however our actual temperature is +21 degrees so we work out the difference which in this case is 0, because our actual temperature is higher then the ISA temperature we refer to the difference with a + sign.

So our temperature is now +21 degrees.

We then apply an ISA deviation so +21 degrees X 120 = 2520 feet.

We then add that to our pressure height 2520 + 7430 = 9950 feet

So 9950 feet is our density height.

Just an update, I havn’t stoped just havn’t been flying in a few weeks, actually its more like a month. Work has had me all over the place recently. Done quite a bit of flying just not in the drivers seat. I have though been working away at the theory side of things as I have several exams coming up where I have to get my head around a few things.

Bought the CR-2 flight computer (Jeppesen) and have been playing around with it. Its quite a cool little gadget for quick calculations, unfortunantly mine didn’t come with a detailed manual so I am doing a bit of work figuring out how it differs from the one used in my PPL book.

I am going to get in some hours next week and finalise my GFTP hopefully, along with that is a final area solo that i’ll be tested on, more updates later.