Features November 2016 Issue
Instrument flight is about precision mated with accuracy. But how can you do that when equally authoritative sources disagree? Brief carefully.
Instrument flight is a game of single degrees, so it should get your attention when numbers don’t match. We’re used to this when flying VOR radials with GPS. The magnetic declination of the VOR is infrequently updated, while GPS calculates it exactly from the latest data and the current location. This can be disconcerting on a VOR approach where the GPS you’re using for situational awareness (or, the actual approach, now that you can) shows a course several degrees off from the chart.