I'm learning how to do cross country flights right now which includes tracking a VOR. My instructor explained what I think was called backtracking, where you get confused because the needle sticks to the left and when you turn to correct it, it keeps moving away from you. I looked through the handbook of aeronatical knowledge and didn't find anything. He explained it, I didn't understand that part. Can anyone clear this up for me?

I believe he means flying the radial in the opposite direction, so your needle reacts in the opposite direction; kind of like backing up a trailer using the rear view mirror.
If that's what we are talking about the easiest and cheapest (of course) way to practice this is using a flight sim. Especially when you have to take into account "drift".
Just a guess.

Speaking of radio navigation; my old man used to use ADF a lot to simplify things; he could set it to the AM freq of the local radio station and fly right to it. I tried this in MS Flight sim, and holy crap, all the navcom data is accurate!

Usually the needle doesnt go back into the center when you correct it if your close to the VOR radio beacon, were you approaching a radio beacon when this happened?

Posted by dohn Usually the needle doesnt go back into the center when you correct it if your close to the VOR radio beacon, were you approaching a radio beacon when this happened?

Yeah, I was getting closer to it and when I tuned it in thats when it happened. It stayed to the left and as i corrected toward it, the needle went even farther left.

Yea you were probabally close to the VOR station, in my experience when your pretty close you shouldn't follow the needle but instead just mainain your heading until the VOR, swings from the " TO" to the " FROM". You are definatley off heading if it swings drastically and you aernt near the VOR. Id check with your instructor about this though just to be 100% sure.

Dohn

Were you on inbound heading on the VOR?

Posted by dohn Were you on inbound heading on the VOR?

Yeah, I had just tuned to it when it went off to the left, the flag was reading "to"

What did your instructor say?

I'm taking my IFR checkride next week so I can tell you exactly what's happening... I suspect this will be a long post but there are literally volumes and volumes that can be written about the humble VOR.

The original question was about reverse sensing and was kind of answered already, but here are some more details since I want to stress some of the finer points that weren't really touched on. (there were 3 or 4 other topics that sprang up, but I don't want to write the instrument book all over again).

Reverse sensing happens almost always when you are trying to fly TO a station, but you twist the RADIAL you're flying over into your OBS (OBS = the twistable ring on the VOR dial) instead of the COURSE to fly. If you know you're flying TO the station but your TO/FROM shows FROM, you are reverse sensing and your needle is backwards. To fix it easily, twist the OBS 180 degrees so the number at top is at the bottom. As you do so, the TO/FROM will flip. Another check to do is to make sure that your heading gyro agrees with your OBS. If you have 180 twisted in the OBS but you are flying a heading of 360, you will get reverse sensing and both your needle and to/from will be wrong.

This stuff is confusing until you know the difference between a COURSE and a RADIAL and how the TO/FROM REALLY works. A RADIAL will ALWAYS point AWAY from the station. You NEVER want to twist the number of a RADIAL into your OBS; always convert it to the desired COURSE and then twist it in. I will repeat this. Always twist the DESIRED COURSE TO FLY into the OBS. NOT the radial you will track along.

Making this conversion is easy. If your desire is to fly a radial AWAY from the station, then your desired course is the same as the radial. If you want to fly TO the station along a certain radial, your desired course is the reciprocal of the radial (+/-180). Just twist the radial to the bottom of the OBS, and the reciprocal course will automatically go to the top.

The TO/FROM needle has nothing to do with your heading and does not actually tell you if you are flying to or away from the station. All that the TO/FROM indicator tells you is whether the currently twisted OBS course will take you TO or FROM the station were you to fly that direction. But as you see, this bit of knowledge is valuable for your situational awareness.

So what happens if you're flying to a station, and you pass over it, and now you're flying away? Do you need to twist in a reciprocal OBS? NO NO NO, because your COURSE has not changed. True, you are now over the opposite RADIAL, but as you crossed over the station your TO changed to FROM and now everything makes sense again.

Make sure all the pieces add up: your OBS should agree with your heading, and your TO/FROM should agree with what you want to be doing. If one is wrong, the other will be wrong as well.

If you use an HSI instead of the traditional VOR dial, you'll never ever make the reverse sensing mistake. HSI's are awesomely cool. But be advised, the first time you try an HSI you'll never want to go back to the old-school VOR needle!

Well that was long after all. Sorry.