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Intercepting Bearings To Ndb's


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I was just wondering in general terms, what is the proper angle to intercept an NDB inbound to the beacon,

 

(A question I got in the sim in Norway during my interview with CHC HS that did not go to well...)

 

The question was as stated above, the answers I gave were not correct according to the guys. My first was 60 degrees, but that was not it.

 

The rule of thumb from the states was:

1. Parallel the course

2. Double the difference and turn to the head of the needle (always to the head of the needle eh?)

 

Then I tried 45 degrees, that was not either, then I said 30?? And NO! so I guess they must have been thinking 90...

 

Anyways, you IFR guys should be able to supply me with the correct answer and then a reference!

Cheers

Winnie :P

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I was just wondering in general terms, what is the proper angle to intercept an NDB inbound to the beacon,

 

Hey winnie,

 

I don't think there is a hard and fast rule. There are far too many variables. The important thing is to realize that you must choose an angle that will allow you to acquire your desired bearing after/before passing the NDB, without exiting/entering airspace or messing up your planned approach etc...

 

I'm not a wealth of info in IFR and look forward to others opinons. I did review the TC instrument procedures and culhanes IR ground school and didn't notice any rules on the subject though.

 

Later,

pl

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If it helps, I always thought it was common to use 90° inbound and 45° outbound,

 

I read that today, but the source is very old, and not entirely reliable anymore...

 

(it is the IF Pocket Simulator by Culver from 1976...)

:(

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Well, in that case, I have never heard of a "proper" angle - and I have a JAA and Canadian IR. I would always use 30 degrees, unless the wind dictates something sharper, so you don't get blown away. That way you don't have too much excessive banking. But then again, maybe you would use what's required, just to get the needle to the other side of the lubber line. I'm seeing an IRE tomorrow, I'll ask him....

 

Phil

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The TC Instrument Procedures Manual should have the answer, unfortunately, I'm on the road and don't have a copy handy. The rule of thumb, as I recall, is:

 

Intercepting outbound - looking at the ADF, you go from the tail of the needle to the desired track plus 45 degrees (tail to desired plus 45)...if the tail initially indicates 250 and you want to intercept the 280 outbound you steer 325 (plus/minus wind); and

 

Intercepting inbound - looking at the ADF, you go from the desired track to the head of the needle and add 30 degrees (desired to head plus 30)...if your desired inbound track is 100 and the head of the needle indicates 150 you steer 180 (plus/minus wind).

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This is the first I have heard of this. How far away are you from the beacon? To intercept a bearing 30 degrees from the one you are on if you are 60 miles from the beacon you dont want to turn 90 degrees. How much wind is there and where is it from? More important is to pick a number and stick with it. Until it doesn't work any more. Then pick another one and stick with that. :lol:

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