The
density altitude/true airspeed function
is also accessed from NAV Menu 1.
Density altitude is the altitude at which your aircraft will perform depending on several
environmental conditions, including air pressure and total air temperature (the tempera-
ture including the effect of speed, read on a standard outside temperature gauge on most
aircraft). True airspeed considers the same factors.
To calculate the density altitude and true air speed:
1. Press
N
and rotate
O
until NAV Menu 1 is displayed.
2. Press
C
twice and rotate
O
to highlight ‘Dalt/tas?’.
3. Press
E
to access the density altitude page.
4. Use
K
and
O
to enter the indicated altitude and press
E
.
5. Use
K
and
O
to enter the calibrated airspeed (cas). Press
E
.
6. Use
K
and
O
to enter the air pressure (‘pres’) and press
E
.
7. Use
K
and
O
to enter the total air temperature.
8. Press
E
and the density altitude and true airspeed will be calculated and displayed.
9. Press
C
to remove the cursor.
If your installation includes components to provide any of the information
required on the density altitude page, they will be used as the defaults.
The
f
uel planning
page will display fuel requirements for both direct-to naviga-
tion and programmed routes. The fuel planning function requires the pilot to know
the initial amount of fuel on board and the flow rate. You may also enter different
ground speeds to view various information based on different travel times. If your
installation is interfaced to a fuel flow sensor, the flow rate and other information will
be used from the fuel flow sensor.
20
REFERENCE
VNAV & Checklists
Density Altitude/True Airspeed Page
Nav Menu 1
Fuel Planning Page
SECTION
1
NAV KEY
Density Altitude &
True Airspeed
250 real 7/14/98 9:32 AM Page 20
