Introduction
Location: 90 NM from KFRM
Aircraft: Cessna 172S
Weather: Great VFR
You’re flying a G1000 NXi Cessna 172S on a VFR flight direct from Waterloo Regional Airport (KALO) in Iowa to Fairmont Municipal Airport (KFRM) in Minnesota. You take off, engage the autopilot, recenter the CDI with a Direct-To, and turn on course. You level off at 6500 feet and run the Cruise checklist.
Watch the video and try to see what’s wrong.
What’s wrong?
- Your engine is incorrectly configured for cruise.
- One or more engine indications hint that you might not reach KFRM.
- Your current navigation is taking you somewhere you don’t want to go.
- You’re currently breaking a regulation.
Watch the Scenario
Watch the Explanation
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Explanation:
The answer is 3: Your current navigation is taking you somewhere you don’t want to go.
The Automatic Flight Control System (AFCS) status box at the top of the PFD shows that the autopilot’s active lateral mode is HDG not GPS. After re-centering the CDI with a Direct-To, you probably forgot to press the NAV button to switch from HDG to GPS (NAV) mode.
Without wind, this probably wouldn’t matter much since the cyan Selected Heading Bug is aligned with the Direct Track to your destination (307°). But there’s a 20-knot wind, slightly to your left. That’s blowing you off course to the right—and you’ll slowly drift right of course. An hour from now, you’d be pretty far off course.
The details are on the HSI (Horizontal Situation Indicator, which is the compass rose and CDI needle combination on the Primary Flight Display, or PFD). The CDI needle is left of course. If the autopilot was configured for GPS (Nav mode on some systems), the airplane would be centered on course by now and staying there.
Furthermore, you know this isn’t going to happen because the magenta Current Track Indicator—the magenta diamond by the heading bug—is a few degrees right of your heading. That’s the direction you’re actually traveling over the ground on this heading (your track). Because the autopilot is still in HDG mode, this track over the ground will continue, you’ll never get back on course, and you’ll end up east of your destination.
Of course, you’d probably figure it out at some point. Good thing you’re the only one on board so no one else will notice.
The last item on the Cruise checklist is “FMS/GPS.” That’s pretty cryptic, but it’s your reminder to always review what the automation is actually doing.
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OK, you’re flying a 172 on a 90 mile flight in perfect VFR weather and you engaged the autopilot. That’s just wrong even if it’s not against regulation.
As long as you hand fly enough to maintain good flying skills, I’d say use and enjoy the autopilot.
Autopilot is set to HDG not NAV