Intercepting a VOR--100 Degree Method??

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rt4388

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rt4388
So I just started instrument training with a new instructor (different from PPL) and we were attempting to intercept a radial for a VOR. The instructor was using some method I had never heard of before and I can't seem to remember how it worked. It went something like this--add 100 degrees then fly thirty degrees to the right/left (obviously not right, but he kept saying 100 degrees and 30 degrees).

Has anyone ever heard of this method before? If so, how does it work? I was taught to simply intercept at a 45 degree angle during PPL training (and to use common sense based off where you are in relation to the desired radial). Will a DPE bust me if I use the 45 degree method on my IFR check-ride?

Thanks for the help!

Edit: Title should obviously be "Intercepting a Radial"--not VOR
 
I dunno but if you become a follower of the magenta line church member ya don't have to worry about these things!

Talk about things with the instructor on the ground. Have him draw a picture. Maybe even with circles and arrows and a paragraph explanation. Inside a cockpit is a terrible classroom.
 
Clark1961 said:
I dunno but if you become a follower of the magenta line church member ya don't have to worry about these things!

Talk about things with the instructor on the ground. Have him draw a picture. Maybe even with circles and arrows and a paragraph explanation. Inside a cockpit is a terrible classroom.
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Thankfully most of the planes I'm in have G1000s. Definitely a believer in the magenta line, but it is nice to go back to the six pack every once in a while. As for the learning on the ground, I couldn't agree more.
 
I'm not sure but I can sort of envision something like that for intercepting the 100 degree radial. Turn to 100 to parallel the radial and then 30 degrees to intercept. Best bet is to ask your CFII to explain it on the ground.
 
Lead by 1% of GS? The '5 T's' over the VOR? Turn, Time, Twist, Transition, Talk?? Where are we intercepting this radial at? The station or 30 miles out? What is the intercept angle? Don't forget about the wind.
 
Never heard of that and it sounds needlessly complicated. You already know your eventual heading just by looking at the top of the CDI needle on the VOR head. Fly a 30 degree intercept from there.
 
Clark1961 said:
Talk about things with the instructor on the ground. Have him draw a picture. Maybe even with circles and arrows and a paragraph explanation. Inside a cockpit is a terrible classroom.
Click to expand...

NDB approaches finally clicked when my CFI had me "walk" a few approaches out in the parking lot before a flight one day.
 
Bill Jennings said:
NDB approaches finally clicked when my CFI had me "walk" a few approaches out in the parking lot before a flight one day.
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While he and the other CFIs laughingly watched you from the window? Hehe I kid I kid!
 
rt4388 said:
So I just started instrument training with a new instructor (different from PPL) and we were attempting to intercept a radial for a VOR. The instructor was using some method I had never heard of before and I can't seem to remember how it worked. It went something like this--add 100 degrees then fly thirty degrees to the right/left (obviously not right, but he kept saying 100 degrees and 30 degrees).

Has anyone ever heard of this method before? If so, how does it work? I was taught to simply intercept at a 45 degree angle during PPL training (and to use common sense based off where you are in relation to the desired radial). Will a DPE bust me if I use the 45 degree method on my IFR check-ride?
Click to expand...
In all likelihood you won't be given a VOR intercept except one that is part of a VOR approach. Your approach to this is perfectly fine: Identify where you are from the VOR, then determine the best way to proceed. Options include navigating to a specific radial, tracking inbound to the station, or tracking outbound from the station.

A note about that YouTube video posted above: The narrator assumes the aircraft's heading and the course selected with the OBS are the same in every example. This, coupled with the spam-like robotic comments below the video seem to indicate that it probably isn't the best source for learning about these concepts.
 
To intercept a radial, you have to turn towards it. The fastest way to get to it is the shortest line, which will be a 90 degree intercept. However this means you have to make a 90 degree turn when you get to it, in order to get on the radial and follow it. The intercept angle that results in the least amount of turning and the least distance flown would be to intercept the radial at its "end" (the end of the course that follows the radial, not necesarily the end of the radial). That is, go direct to the where the radial ends (the VOR, or some DME away from it that is a waypoint where the course you are navigating "ends"). Somewhere in between is USUALLY where you want to be. It all depends on how far off the radial you are and how far away the end of the route following the radial is.

Best thing to do is to draw a VOR, draw some radials and draw an airplane icon with it's trajectory and intercept some radials on paper. Nice to have a ruler and a protractor for this kind of exercise. There really is no formula for picking an angle to intercept, you just have to evaluate the situation and pick an angle that gets you where you want to be.
 
All this math makes my head spin. While I'm not a child of the purple line, I do have an HSI. You intercept a course the same way you'd enter a road. PIck a comfortable cut at the radial and if the wind or whatever shows you're not converging make it more aggressive.

Even without an HSI, you can just visualize where the radial is on your DG.
 
flyingron said:
All this math makes my head spin. While I'm not a child of the purple line, I do have an HSI. You intercept a course the same way you'd enter a road. PIck a comfortable cut at the radial and if the wind or whatever shows you're not converging make it more aggressive.

Even without an HSI, you can just visualize where the radial is on your DG.
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And note that Ron didn't say "you intercept a VOR course the same way you'd enter a road." You intercept a VOR course the same way you'd intercept a GPS course.
 
Harold Rutila said:
In all likelihood you won't be given a VOR intercept except one that is part of a VOR approach.
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:confused2:
I must be misunderstanding your post. I can't even count the number of times I have been instructed to intercept an airway. Many more times than I have even flown a VOR approach.
 
MauleSkinner said:
And note that Ron didn't say "you intercept a VOR course the same way you'd enter a road." You intercept a VOR course the same way you'd intercept a GPS course.
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But in either case I think it's unnecessary to make it any more complicated than the way you would enter a road. It's much easier with an HSI, of course, but that's essentially what I do, either with a VOR course or a GPS course. I choose an angle that looks about right, depending on the winds, which usually amounts to somewhere between 30 and 45 degrees. If I'm not converging fast enough, I make the angle sharper. My GPS shows cross-track error for a GPS course, which helps a great deal in determining if I'm converging before the CDI starts to move, assuming it's full deflection to start with. For a VOR course, you can twiddle the OBS to see how many degrees you still have to go to reach the desired radial.
 
Harold Rutila said:
In all likelihood you won't be given a VOR intercept except one that is part of a VOR approach. Your approach to this is perfectly fine: Identify where you are from the VOR, then determine the best way to proceed. Options include navigating to a specific radial, tracking inbound to the station, or tracking outbound from the station.

A note about that YouTube video posted above: The narrator assumes the aircraft's heading and the course selected with the OBS are the same in every example. This, coupled with the spam-like robotic comments below the video seem to indicate that it probably isn't the best source for learning about these concepts.
Click to expand...

They do exist, it's actually a standard procedure for a few routes in SoCal. "After departure fly heading 360 to join the xyz radial of abc VOR".
 
I've been told to join airways, sometimes given a heading, sometimes not. A more common situation is intercepting a LOC or other approach course.
 
I have to say I just don't understand your question rt4388. As others have said, you probably need to get with your CFII on the ground before the next lesson and have him/her draw it on a piece of paper so you will understand what you are supposed to be doing.
 
When it comes to VOR/GPS navigation, including holds, I've had 100% success rate with all of my instrument students going back 15 years by using the very simple method of drawing and visualization. I've never taught any of the tricks, such as "use your thumb and forefingers on the DG", "figure out the quadrant for an approx. heading to fly using to/from flag and CDI," etc. In my experience the only way to teach the pilot how to do it right every single time is to get him or her acclimated to visualizing the intercept, hold, or whatever from above and this SA sticks with them long after their primary instrument training is over.

For a little while it's necessary to draw, but after a time the mind does it without needing paper. And this process may be slow for 2-3 lessons but it eventually speeds up to the point that my students are able to visualize what they need to do in a couple of seconds. From that point on it's very obvious which heading they should fly, how to set the OBS, etc.

Just my .02!
 
Clip4 said:
Depends on where you are intercepting them from. The earth is rotating and on a orbit around the sun. The VOR locations are a moving target.
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They are stationary relative to aircraft.
 
MauleSkinner said:
Not like in the old rho-theta RNAV days...people used to move VORs all day long and not tell anybody where they put them!
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I believe they moved waypoints, not the VOR station itself.
 
Like many responders, I have not heard of this method. I use to teach FROM TOP and TO BOTTOM. Top/Bottom referring to the VOR receiver. This memory item helps place the correct course when twisting the CDI. So if you are S of the VOR flying N, you are on the 180 degree radial TO the VOR, so TO BOTTOM would place the 180 at the bottom of the VOR. Heading is 360 and VOR CDI is 360 (which should always match)
 
I don't even understand the original post, quite likely the instructor has some method, can be even reasonable but he is unable to convey what this method is, impossible to pass judgement.
 
The Universe is expanding. All VORs are always getting farther away. Always. ;)
 
yeah we still use A/A TACAN in the USAF. Hardly a primary means of ranging anymore, mostly training, and for those of us red-headed stepchildren without that fancy A/A radar cape.
 
Clip4 said:
The earth is rotating and on a orbit around the sun. The VOR locations are a moving target.
Click to expand...
I'm picturing an approach plate for the sace shuttle, with step down alitudes in the flight levels and an IAF at 200,000 ft
 
This young man Bret, does a great job describing the Shuttle reentry profile, even though it was flown before he was old enough to remember.

 
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