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:

Conventional localizer navigation with a standard VOR/LOC indicator requires complex mental rules to determine whether to "chase" or "pull" the Course Deviation Indicator (CDI) depending on the course and direction of flight.
The Horizontal Situation Indicator (HSI) simplifies localizer navigation by combining a gyro heading indicator with the VOR/LOC display, rotating the instrument with the aircraft's heading.
When using an HSI, consistently setting the localizer's inbound front course into the Omni-Bearing Selector (OBS) is crucial.
With the HSI properly configured, pilots can always correct course deviations by "chasing the needle," eliminating the need for complex mental adjustments previously required for front or back course navigation.

See a mistake? Contact us.

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.