The problem is that the route would take us over some rough terrain in the Diablo Range Mountains.  While technically there's no reason we can't do that, the route leaves few or no options in case of a forced landing.  And even after a skillful landing, there's no cell phone coverage down in those canyons to get help or even a ride.  So maybe we want to pick a route more around the periphery of those mountains.

But we're not throwing the GPS out.  In fact, it still shines brightly for this trip.  So now we need to look in the GPS manual or book, and find out how to enter a flight route into it.  Although every GPS manufacturer has a different style, the route will always be a series of waypoints.

So we need to pick a route.  A good route should be easy to verify visually in VFR flight.  Instead of just VOR and NDB stations, we can use any intersection or visual waypoint on the map.  I like to use the web site skyvector.com for this.  It lets me try out and plot a route.  If I don't like it, I can add or remove waypoints and plot a new route.  If we enter "KRHV KMOD", we can see those nasty mountains in our way.  As we look for a route around them, click on the SFO Terminal chart for some more details.  There are visual waypoints at Calaveras Reservoir (VPCAL) and Del Valle Dam (VPDAM).  You can recognize them by the magenta flags and a 5-letter waypoint name starting with "VP".  VFR waypoints also use the diamond waypoint symbol which originated on IFR charts.

So now let's try the route "KRHV VPCAL VPDAM KMOD" on skyvector.com.  That looks much better.  You wouldn't want to stray any closer to the Restricted Area R-2531 than this.  But it has a ceiling of 4000' MSL.  If in doubt, fly above it.  You should fly at least that high anyway because there's a 2986' peak south of your route in that area.  5500' is a good VFR cruising altitude for the eastbound part of the flight - fly at least 4500' while passing the 3000' peak and 4000' Restricted Area R-2531.

Remember that you want some safety buffer so that the radar controllers don't think that you busted restricted airspace - they're not looking at your GPS.  So use at least a mile off any side and 500' above, preferably more.  Any good GPS should also show that airspace to you.

Those same waypoints you entered into skyvector can now be entered into your favorite flight planning software or web site to meet the requirement to verify that we know we have enough fuel.  You can use the same waypoints to file a VFR flight plan.  And the same waypoints can be entered into the route on the GPS.  While you're at Reid-Hillview, you don't have to enter KRHV.  So enter VPCAL, VPDAM, and KMOD.  Activate the first leg.  Then after takeoff, the GPS should show you a line on the map.

Select the GPS input for your CDI and you can have right or left indications to get you back on the course centerline all the way to Modesto.

Can you do that?  With practice it'll become easy.  Give yourself several flights that you know how to do without the GPS to practice and figure it out.  You'll see that it takes some time to learn the menus in each manufacturer's GPS.  But once you do, it'll be as fun as you expect it should be.  It's just a bigger step than most people think to get to that point.

As it turns out, I picked a route that can be flown just about as easily without a GPS.  Modesto has a VOR on the field.  It's a good idea on initial practice flights with a new GPS to go somewhere that you can fall back on what you already know, just in case.  So even if you don't pick this particular route, use that idea.

So here's an exercise... Practice this until you can explain to another pilot or student pilot what you're doing.  Then you know you've got it.

• Start from your home airport - so it doesn't have to be KRHV.
• Find another public airport within a short cross-country distance, about 45-80nm, where the direct route would take you over mountains, restricted airspace or something which makes the direct route not a good idea.  In the previous example, we had to contend with the Diablo Range Mountains and Restricted Area R-2531.
• Pick additional waypoints which will go around the problem.  VFR waypoints are the best choice to start with because you want to see them to know for sure you're in the right place.  Later as you get good at it, you can advance to using any waypoints in the system that suit your navigation, or even latitude and longitude.  But for starters, keep it simple.
  

For example, if your home airport is Palo Alto (KPAO), then a direct flight to Tracy Municipal Airport (KTCY) would go through Restricted Area R-2531.  So we have to go around.

That's actually not so tough.  It's just a matter of recognizing that you still have to plan your route.

Use this technique to plan your next VFR flight.  The difference from using radio navaids is that you can fly to any waypoints you want along the way and use them all like navaids.  Of course, if there are no problems or obstacles with the direct route, then it's fine to use it.  The point here is to check it for problems, and know how to use the GPS to fly a route around it.