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:

A Horizontal Situation Indicator (HSI) simplifies localizer approaches by combining a gyro heading indicator with a VOR/LOC navigation instrument, eliminating complex mental corrections required by traditional indicators.
The fundamental rule for flying localizer approaches with an HSI is to always set the localizer's inbound front course under the Omni-Bearing Selector (OBS).
When the HSI is properly configured by setting the inbound front course, pilots can consistently correct for course deviations by simply "chasing the needle," regardless of whether they are on the front or back course.

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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.