Lowrance electronic AirMap 2000C - Manual (Page 62)

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Vertical Navigation Calculator
With the Vertical Navigation Calculator, the AirMap 2000 can help you
decide when to let down for an approach to an airport. To get to the verti-
cal navigation calculator menu: while in Aviation Mode, press
MENU | MENU |
↓ to
A VIATION C ALCULATORS
| ENT |
↓ to
V ERTICAL N AV
| ENT .
(The command only works when you are navigating to a waypoint.)
In the following example, we're travelling to the Wichita Mid-Continent
airport in Wichita, Kansas. Its identifier is shown at the bottom of the
screen – KICT. We are travelling at 4500 feet, and need to be at the pat-
tern altitude (about 2300 feet) by 5 nautical miles from the airport using a
450 fpm descent.
After determining the above information, use
↑ or ↓ to highlight each
field, then press ENT . In each box, use the arrow keys to enter the data.
When you’re finished, highlight O
N
next to the "Vertical Nav" label and
press ENT . A screen similar to the one below appears.
The solution to our vertical navigation problem shows at the top of the
screen. Our current altitude is 4500 feet and at our current airspeed,
we should begin our descent in 44 minutes and 20 seconds. If we main-
tain a 450 fpm descent starting in about 44 minutes, then we should
reach pattern altitude 5 nautical miles before we reach the airport.
You can watch the clock count down your approach. If you increase
your speed, the clock will decrease more quickly. If you slow down, it
will take longer. Either way, when you reach the point at which you
should begin your descent, the box at the top of the screen changes.
Now in place of the timer, it indicates that you
should be descending.
Below that, it shows the altitude you should be at.
Vertical Navigation Calculator