Heading Set Knob?

[Praetorx]

Whats the point of the heading set knob? I understand the course set knob but only today I noticed the heading set knob. Is it used a lot? Have I been missing out on something?

[JCook]

The heading knob is used to set a reference bug (also a numerical counter) for a magnetic heading. For example if you want to fly a 073 degree heading you turn the knob until the readout is 073 and then you fly that heading by having that at the top of the HSI. The course set knob on the other hand is used with radio navigation / TACAN.

 

Hope that helps.

[Praetorx]

Where is the reading of the heading knob located?

[JCook]

On this type of HSI there is no heading counter, you'd probably see that in a EHSI - instead you use the heading bug. As you turn the HDG knob you'll see the bug move around the gauge and that is how you set the heading in the A10. Turn the knob to the heading you want to go, 073 in my example then turn the plane left or right (usually whichever gets you to the heading quicker) and level out with the heading bug at the top of the HSI which will be 073. Make sense?

[Praetorx]

Yeah, is it just a backup system incase the heading thing on the HUD fails?

[JCook]

You could look at it that way - redundency. Not sure about flying instrument approaches in IMC with the HUD - I would think that would be done looking at the gauges - in which case the HSI heading could come in to play. You might use the heading bug to help set an intercept course to an ILS approach for example.

[BlueRidgeDx]

In the A-10 (and most other tactical aircraft) the Heading Bug is nothing more than a visual reminder of the desired heading. You would usually set it to runway heading for takeoff and landing, to anything relevant during cruise, to the final attack heading given by the JTAC, that sort of thing.