#LOCALIZER BACK COURSE PORTABLE#

The HSI also provides a To/From indication that flips as you rotate the pointer.

When operating with a VOR, the CDI can be centered with either the head or tail of the pointer on the correct number on the compass card, just like a VOR indicator. The rectilinear CDI moves to either side of the pointer with the CDI centered, it becomes part of the shaft of the course pointer.īut the term course pointer isn’t necessarily accurate. The HSI has a short pointer that you set to the desired course on the compass card around the outside. In this fashion, the VOR indicator’s course pointer and CDI would rotate with the heading. The answer was the horizontal situation indicator (HSI) that put a VOR/LOC indicator inside the heading indicator compass card. But relative angles of the current position remained difficult to envision, particularly with the windshield-wiper movement of the less expensive indicators versus the more intuitive rectilinear movement. This gave the pilot a separate indication of radial and the relationship to a desired course on the VOR indicator. The RMI needle points to the VOR just like an ADF pointer. Some pilots added a radio magnetic indicator, RMI. The problem with the basic VOR display is that the pilot needs a graphic mind to maintain situational awareness and it was easy to get confused sorting out course from radial from heading and position, while deciphering what the To/From flag was telling you. Add a little clever manipulation in the indicator, and you can select a specific course you want to fly to or from the station and the indicator’s course deviation indicator needle (CDI) will tell you which way to turn to get back to the selected course.

To better understand the HSI, we’ll have a quick VOR review, then see how the HSI brings it all together.Ī VOR signal provides the exact angular relation of the receiver to the station.

#LOCALIZER BACK COURSE PORTABLE#

I get a lot of HSI questions-although rarely that convoluted-now that so many panel mount and portable devices contain an electronic HSI.

Your HSI course points back to the runway and you’ve got a right needle deflection. You’re outbound on the localizer back course. Let’s start with an old hangar-flying puzzle.

Localizer back course