Reverse Sensing

In last months IFR Clinic we discussed how VORs work. Boring and repetitive as that is, we needed to start there to get the basis for understanding a localizer and a localizer back course using a conventional dedicated navigation indicator (VOR/LOC) and the need to sometimes chase the CDI to correct, and sometimes to pull it. Theres too much material for a proper review, so lets just skip right to the good stuff.

Frank Bowlin

Wednesday, June 08, 2016 at 12:00 AM ET

Verified

Key Takeaways:

Traditional localizer approaches using VOR/LOC indicators require complex mental rules to determine if the course deviation indicator (CDI) should be "chased" or "pulled," depending on the aircraft's direction and position relative to the localizer.
The Horizontal Situation Indicator (HSI) simplifies localizer navigation by combining a gyro heading indicator with the VOR/LOC display, allowing the CDI to rotate with the aircraft's heading.
By properly setting the HSI to the localizer's inbound front course, pilots can consistently correct for course deviations by always "chasing the needle," eliminating the need for complex mental adjustments on both front and back courses.

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In last month’s IFR Clinic we discussed how VORs work. Boring and repetitive as that is, we needed to start there to get the basis for understanding a localizer and a localizer back course using a conventional dedicated navigation indicator (VOR/LOC) and the need to sometimes chase the CDI to correct, and sometimes to pull it. There’s too much material for a proper review, so let’s just skip right to the good stuff.

The Rules

Rule #1

Always (always!) put the localizer inbound front course under the omni-bearing selector (OBS). The OBS setting doesn’t matter to the electronics on a localizer, but this is a good rule as we’ll see a bit further down.