Plane & Pilot
Sunday, August 1, 2004

Mastering The Panel-Mounted GPS Part 1: VFR Use


Bendix/King, Garmin, Chelton? At first glance, they all seem so different, but are they really? It turns out they have a lot in common.


Learning to use even one of the modern IFR-approved GPS maps, let alone several of them, is challenging. Understanding the capabilities of a device requires as much class time as learning how to operate it. The how can be very different from unit to unit, but the what is surprisingly similar.
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Since it helps to organize the recall of data from the unit, there are advantages in creating a more extensive flight plan rather than going direct. The databases are alphabetical, but can be categorized by all the nearest things (waypoints, airspaces, centers, FSS stations) or by your flight-plan waypoints. So, if you name a departure airport, rather than go direct to your destination, and include airports along the way, you can quickly find frequencies and other information about them. Also, the active flight-plan page and your map data fields will show selectable info on each waypoint, like distance, ETE or desired track. If you don’t really want to fly that zigzag route, go Direct-To your destination within the flight plan. This won’t change your flight-plan list, so you can still call up information on each waypoint quickly.

You may want to include user waypoints in your flight plan. If you’ve flown out of the Seattle area with its many TFRs, you may have been given a clearance to some lat/long point to miss them, then gone direct to your first waypoint. You can do that by making a user waypoint at that lat/long and putting it into your flight plan.

User waypoints can be created in several ways. Just push the cursor while you’re on the map page and select ENT (on the 430 or 530) or MRK (on the CNX80) to make a waypoint at your present position (enter it again to confirm it). On the KLN94, press Enter twice while on the Nav2 present position page. Later, you can go to the user waypoint list and edit the default name to one you choose. You also can make a user waypoint defined either by its lat/long coordinates or its radial and distance from any waypoint in the database.

Making a judicious string of waypoints en route to your home airport can be useful later if you come home in low visibility and marginal VFR situations. In airspace-rich areas like Los Angeles, this is a good way to thread your way around the basin.

Direct-To Operations
Many pilots use Direct-To for a quick and easy flight plan. If you have a more extended flight-plan list, you can still use the Direct-To operation. If you opt for a Direct-To waypoint off of the plan, your map will show the new flight-plan course as a magenta line to that waypoint. Your active flight-plan list is unchanged, however, and its waypoints (but not the legs) may still be shown on the map. If you later eliminate the Direct-To operation, your former flight plan is still active. To eliminate a Direct-To operation, you can cancel it in the KLN94, or 430 or 530, or just activate a leg in your flight plan in the CNX80. The 430 or 530 elimination trick is to push Direct, Menu and Enter (the DME acronym trick). For the Bendix/King, push Direct, Clear, Enter. Using Direct-To within your flight plan also is a useful tool. It takes you directly from the present position to a selected waypoint in the plan and leaves the list alone.

The Garmin 430 or 530, and CNX80 do a lot more. On the 430 or 530 Direct-To page, you can choose any waypoint in the database or select one from your flight-plan list or nearest waypoints and then choose your course to that waypoint in the CRS box (the default choice is direct from the present position).

The CNX80 does all that and more. Pushing the Direct key brings up a set of soft keys, labeled Direct, Hold, Dest, FlyLeg, CrsTo, CrsFr and OBS. This is where you activate specific legs (here, the one ending in GMN, which has the cursor on it) or go to or from a waypoint on a specified course. With the KLN94, you can specify the OBS course numerically only if the unit is not switched to your CDI.




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