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The density altitude/true air speed function is also accessed from NAV Menu 1.
To calculate the density altitude and true air speed:
1. Press N and rotate
O
until NAV Menu 1 is displayed.
2. Press
C
and rotate
O
to highlight the ‘Dalt/tas?’.
3. Press
E
to access the density altitude page.
4. Use
K
and
O
O
to enter the indicated altitude (ialt) according to the altimeter.
Press
E
.
5. Use
K
and
O
to enter the calibrated air speed (cas). Press
E
.
6. Use
K
and
O
to enter the air pressure (‘pres’) obtained from local weather stations or
from the altimeter (assuming the altimeter is calibrated). Press
E
.
7. Use
K
and
O
to enter the total air temperature according to aircraft instruments.
8. Press
E
and the density altitude and true air speed 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 displayed as the defaults.
The Fuel Planning page will display fuel requirements for both direct-to naviga-
tion, and for programmed routes. The fuel planning function requires the pilot to
know the initial amount of fuel on board and the flow rate of fuel in the aircraft. The
fuel planning feature allows you to enter different ground speeds to view various
information based on different travel times. If your installation has interfaced a fuel
flow sensor to the GPS 150, the flow rate and other information will be used from the
fuel flow sensor, and do not need to be entered manually.
15
REFERENCE
Density Altitude/
True Air Speed
Section
1
NAV Menu 1
Density Altitude/True Air Speed page
150man rev E 7/24/98 3:10 PM Page 15