User manual
Aerosoft Aspen Extended 1.00
Page 13
The real problems start when things go wrong. At a normal landing you have almost all of your power to get
you out of a problem, but at high Density Altitudes you might not have much to use, and in the thin air the
difference between max speed and stall speed is very small.
If you’ve never flown at a high altitude airport before, you run a major risk when you do so for the first time
because on your standard checklist there will be the item [Full Rich Mixture]. Now if you do that at 8,000’ you
run a high risk of the engine stalling on you. If you are lucky this will not happen before the engines slows
down on the rollout, but if you are not it will die on you before you hit the next item on your checklist. Make
sure you keep high rpm on the prop but it is easy to over-rev the prop shaft so keep the needle just below the
red line.
HOW DO I ESTIMATE THE DENSITY ALTITUDE?
Actually the correct calculation is very complex and involves tables and many variables, but as always in
aviation there is a rule of thumb that is close enough for almost any purpose.
Set your altimeter to 29.92 (1013).
Read the altitude indicated. This is your Pressure Altitude (pa)
Now find the closest figure in the first column.
In the correct temperature column, you can read a good approximation of the current Density
Altitude.
41°F / 5°C
50°F / 10°C
59°F/ 15°C
68°F/20°C
77 °F/25°C
85°F/30°C
94°F/34°C
104°F/40°C
4000
3,750
4,350
4,900
5,450
6,000
6,550
7,100
7,650
4500
4,400
5,000
5,500
6,050
6,600
7,150
7,700
8,250
5000
4,990
5,550
6,100
6,650
7,200
7,750
8,300
8,850
5500
5,600
6,200
6,700
7,250
7,800
8,350
8,900
9,450
6000
6,200
6,800
7,300
7,850
8,400
8,950
9,500
10,050
6500
6,850
7,400
7,950
8,500
9,050
9,600
10,150
10,700
7000
7,500
8,000
8,550
9,100
9,650
10,200
10,750
11,300
7500
8,100
8,650
9,150
9,700
10,250
10,800
11,350
11,900
8000
8,700
9,250
9,750
10,300
10,850
11,400
11,950
12,500
8500
9,300
9,900
10,350
10,900
11,450
12,000
12,550
13,000
Note the italic numbers actually give a Density Altitude BELOW your actual altitude.
If the temperature is below 50° you can almost always assume Density Altitude will not be an issue, just as it
will almost never be at an airport near sea level.