You're flying along at cruise altitude and need to descent to your destination. You want to descend at around 500 fpm...what do you do?
Flip out an E6B..start playing mental gymnastics? If you're flying with Navgps Pro, all you do is specify the destination altitude.
Bring up the Direct-to dialog and enter the altitude you'd like at the destination in units of hundreds of feet. For example, 2000 ft msl would be 20 and 120 ft msl would be 1.2 etc.
Navgps Pro will display a vertical scale down the right side of the moving-map. The CDI needle behaves like a traditional glide-slope but the tolerances are higher - it's +/- 3 degrees. The number below shows by how many feet you're off the initial target slope path. The number at the top shows your DVS (desired vertical speed). This is the speed you should be descending at - that is it should be the reading of your VSI instrument.
Now let's get back to your problem. With Pro, just set the destination altitude as explained above and then wait until the DVS is around -500 and then start descending at that rate.
Note that the DVS is dependent your your ground-speed. If you descend without powering back, your ground speed will increase and so will your DVS. If you'd like to descend at a given rate but do not want to power back, then initiate your descent a little bit before your target DVS. For example, in the above case, around -450 DVS then as you descend...your gs will increase and your DVS will be
close to -500.
This feature applies to both descents and climbs.
Just before you initiate you your descent/climb, you should bring up the Direct-to dialog (press B1 button), no need to change anything and then close it (press the Action-button). This will cause Navgps to re-compute the optimum slope, the CDI will be centered. Now following the DVS will keep the CDI centered.
Also, this feature can be part of your flight-plans using the Plan>>Enter menu option. Enter the navaid identifier, then '@' and then the desired altitude in the above format. For example, let's say you want to be at 3500 ft msl at the BREZY fix. Enter "BREZY@35".
If you do not enter an altitude for all the waypoints in your flight-plan, Navgps will assume you want to climb/descent at a constant rate to the destination navaid.
For example, if your current altitude is 8000 msl, plan "A B C@20" means you want to be at C at 2000 ft. Navgps will guide you at a constant rate thru A and B to C. If that's not what you want, then you need to enter the altitudes for A and/or B also.
IMPORTANT NOTE: When VNAV is active, Navgps will prompt to synch the gps altitude to your altimeter reading. This should be done in straight and level flight.
