This is a beginner question and perhaps this
isn’t the place, but what’s a HSI? I know what is IS (vor and DG in one, yes?) But I dont know what
it offers over the vor and dg that you already
have. I suppose its some IFR situation? The 172 I know doesn’t have it. Obviously a student pilot here. Thanks.
Landon
This is a beginner question and perhaps this
isn’t the place, but what’s a HSI?
It is, as you understood, a heading indicator with a CDI built in. The big advantage over separate HI and CDI is that the CDI needle turns with the compass card. This allows you to immediately see and appreciate your intercept angle, and eliminates reverse sensing. It also makes for a more compact instrument scan.
In the SR20, another advantage is that it saves an instrument hole, which are in short supply!
This is a beginner question and perhaps this
isn’t the place, but what’s a HSI?
It is, as you understood, a heading indicator with a CDI built in. The big advantage over separate HI and CDI is that the CDI needle turns with the compass card. This allows you to immediately see and appreciate your intercept angle, and eliminates reverse sensing. It also makes for a more compact instrument scan.
In the SR20, another advantage is that it saves an instrument hole, which are in short supply!
The HSI can be usefull for VFR flight in the pattern too. Detune the associated NAV radio, so no station is being received. Set the radial arrow to the runway heading. Now you can see whether you are still parallel to the runway on downwind past the numbers without doing any math or looking over your shoulder. You can make your base leg perfectly square. Of course you have to factor in winds. 