HSI Question

[Swerpipe]

One Special Feature...

HSIs have one special feature that many pilots miss. When you are on an intercept heading and the course becomes alive, you should wait until the "needle" touches the line from vertical (lubber line) and then turn (left or right) to keep these two lines touching each other as you intercept course. To keep these two lines "touching" each other you will need to vary your bank angle from small intitially then larger then smaller. What is great is that the HSI will "coordinate" your turn as you intercept the localizer just like a flight director would.
I realize the difficulty of explaning this without a video or a live sim in front...

 

[fokkers&beer]

The slave and free thing have to do with coupling it to the flux compass. Flux compass don't work, put it in free, adjust it and it works like a DG, no automatic north capabilities.

 

[Tinstaafl]

There's a slight catch to be aware of when keeping the lubber line in contact with the CDI: If there's a signifcant wind from the other side of the desired course ie a x-wind once on course that was pushing you away from the track & not towards it, then eventually the HDG achieved while keeping the two points aligned will be the wind correction angle & the a/c will parallel the desired course instead of intercepting it.

The good news is that once you achieve track you'll already know what drift allowance you'll need.