Descentomater Basic Operation for FSX freeware SR-71a:
Shift-7 for the panel.
1) Click PWR in lower right. If pwr is already on, powering off and back on clears the destination.
2) When 1st powered on, window is prompting for destination ICAO address. Keyboard is enabled. Simply type the four-letter code.
3) Click ENT to the left of the power button.
3) Click +- on the TD button (upper right) to move the orange arrow in the center of the display to adjust how far from the runway the meter ends its calculation.
4) Click (enable-green light) ALT ft button on the upper left to tell the meter the altitude the calculation will end (if not the runway altitude.) The window display changes to prompt for the altitude. Keyboard is enabled. use the main keyboard to enter the number and click ENT on the lower right.
Example:
I'm 400 miles out of PHNL and want to set up the descent meter. My typical scheduled descent will start manually around 325 miles from PHNL at 80K ft Mach 3.2. Note that the meter RANGE is direct Line Of Sight (LOS.) If you are using a flight plan, the FP estimated distance (plan loaded in FS GPS is very handy for this) is more accurate.
Power the unit and type PHNL (click ENT.)
Click the TD button to advance the arrow to 20 miles (I want to be at my approach altitude 20 miles from the runway.)
Click the ALT ft button and in the window, type 3500 and click ENT on the lower right.
The gauge is now all set up. As is typical for all descent meters, they cannot comensate for the high speed, high altitude and rapidly changing descent rate and speed changes. The gauge is not useful until around 35K ft and mach 1. Until then, follow the manual published schedule which will get you on the target altitude and speed required for the meter to become useful. The gauge will help prevent descending too fast or slow those last critical miles where the fuel burn is critical. Until then, the gauge needle will indicate in the red. As you increase the descent rate, the needle will drop (indicating you need less descent rate to reach the target. The orange text in the window is the calculated direct distance to the DESCENT TARGET DISTANCE you entered with the DT button.
As you get close to the 150 miles, Mach 1 and 35K ft meter target, the descent meter will be near or in the yellow range. Keep the gauge in the upper yellow early in the calculated descent and upper green for the remainder of the descent. The last 30 miles or so with the needle in the green, you have the option to click the AUTO button and have the meter control the descent to a perfect altitude target. This works very well.
