MECIR: ADF Intercepts
Join Date: Apr 2008
Location: Perth
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Personally I never had an issue with transposing the ADF needle when I learnt to do intercepts. I was taught all the rules etc originally but it wasn't until I actually did my ME-CIR that I was taught the method below.
The DI can be used as a map like a few of the others have said. The center of the DI being the station position and the tail being the aircraft position. Before I go on, I'll just clarify a point that will come up;
QDM = track to the station
QDR = track from the station
It's what I use currently so I hope it doesn't cause confusion.
eg:
Tracking 360 QDM (ie to the station)
If you wanted to intercept a QDM of 330 then you would walk through the 4 steps you most likely have been taught already.
1) Where am I?
-> transpose needle you are on the tail position
2) Where do I want to go?
-> Set HDG bug to Track or find it visually. In this example you want to track 330 QDM.
3) How do I get there?
-> Divide the DI in half through the track you wish to fly (QDM or QDR it doesn't matter). You then choose an intercept heading which is on the opposite half of the DI to the aircraft position determined from step 1 within 90 degrees of the desired track. Any intercept heading that passes over the station will result in you intercepting track overhead (eg HDG 360).
Notice that a heading of 330 to 360 will intercept the track after the station or overhead the station and is not going to be acceptable so you would need to do an intercept greater than 30 degrees. (Edit: Highlighted headings of 330 through to 060 not showing up when previewed but that is the range of headings you would be looking at for the intercept).
4) Is it working?
-> Turn onto the intercept heading and check to ensure that either the head of the needle is dropping toward the desired track or the tail of the needle is rising to the desired track.
Just remember always turn the shortest distance to your intercept heading that you select (removes the need to remember the OIL mnemonics).
Now this is only one method of doing the intercepts and it may not be the best for you. Others have mentioned the parallel track method (turn onto desired track and see which way needle points) and the basic transposition and rules methods (OIL etc).
The method above works for both QDR & QDM intercepts and I find it easy to apply quickly. Just remember if all else fails get above your minimums and re-orientate yourself. Better safe than sorry.
Hope it helps
The DI can be used as a map like a few of the others have said. The center of the DI being the station position and the tail being the aircraft position. Before I go on, I'll just clarify a point that will come up;
QDM = track to the station
QDR = track from the station
It's what I use currently so I hope it doesn't cause confusion.
eg:
Tracking 360 QDM (ie to the station)
If you wanted to intercept a QDM of 330 then you would walk through the 4 steps you most likely have been taught already.
1) Where am I?
-> transpose needle you are on the tail position
2) Where do I want to go?
-> Set HDG bug to Track or find it visually. In this example you want to track 330 QDM.
3) How do I get there?
-> Divide the DI in half through the track you wish to fly (QDM or QDR it doesn't matter). You then choose an intercept heading which is on the opposite half of the DI to the aircraft position determined from step 1 within 90 degrees of the desired track. Any intercept heading that passes over the station will result in you intercepting track overhead (eg HDG 360).
Notice that a heading of 330 to 360 will intercept the track after the station or overhead the station and is not going to be acceptable so you would need to do an intercept greater than 30 degrees. (Edit: Highlighted headings of 330 through to 060 not showing up when previewed but that is the range of headings you would be looking at for the intercept).
4) Is it working?
-> Turn onto the intercept heading and check to ensure that either the head of the needle is dropping toward the desired track or the tail of the needle is rising to the desired track.
Just remember always turn the shortest distance to your intercept heading that you select (removes the need to remember the OIL mnemonics).
Now this is only one method of doing the intercepts and it may not be the best for you. Others have mentioned the parallel track method (turn onto desired track and see which way needle points) and the basic transposition and rules methods (OIL etc).
The method above works for both QDR & QDM intercepts and I find it easy to apply quickly. Just remember if all else fails get above your minimums and re-orientate yourself. Better safe than sorry.
Hope it helps
Join Date: Nov 2008
Location: The Shire
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GG i like the sound of your method, but i dont quite understand it from your post, could you perhaps explain it in a little more detail with the aid of an example.
i.e: you are tracking on the 280deg outbound and want to intercept the 160deg inbound.
i.e: you are tracking on the 280deg outbound and want to intercept the 160deg inbound.
As Chuck said, imagine the centre of the RMI/ADF is the aid and you are on the tail. If you are outbound on the 280, and you want to go inbound on the 160 have a look at the situation. 160 inbound is actually the 340 bearing from the station, which is to your right. Pick any heading 90 degrees to the right of 340 and adopt one. Once the head of the needle is within 5 degrees of pointing 160 inbound, turn onto the heading. Use the drop the head method for accurate tracking on your inbound track.
GG
