VOR Correction

MNFlyboy

MNFlyboy

Well-Known Member
So here's a question. During a VOR check, the OBS on the Nav1 shows to be +4 degrees off (during the VOT check, a 184 degree OBS is centered up with a TO indication) which is just barely legal. When you go flying, do any of you add that error to your desired course in order to track the desired route? If a victor airway was a 111 degree course, would you twist the OBS to 115? Does this make sense or am I off in left field here.

The reason I ask is because the student and I went flying, and we tuned in the desired course to be flown without any correction and ATC kept giving us "off course" advisories.

Discuss
 
§ 91.181 Course to be flown.​

Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:
(a) On an ATS route, along the centerline of that airway.
 
gotWXdagain said:
§ 91.181 Course to be flown.


Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:
(a) On an ATS route, along the centerline of that airway.
Click to expand...
That doesn't answer his question in the slightest.

To the OP, I've always still flown the airway by the numbers on the chart, not corrected for error.
 
I'd fly as is, just because 184 is 4 degrees off doesn't mean that 180, 188, or for that matter any other OBS would be off by 4 degrees as well. What I'm saying is that degree error isn't constant around 360 degrees
 
Yeah I would do what the others above have said and just fly it as is. If the VOR check is within acceptable standards, ATC can just deal with it. I wouldn't try and get creative with it.
 
IslandFlyer said:
One more note: I would also insure your VOR check is properly documented as well just in case you need to prove it for some reason (DEPS)....date, error, place, signature.
Click to expand...


Agreed, a little CYA is easy peasy and goes a long way to help you sleep well.
 
Thanks for the responses everyone, great insight! I agree with what your saying, and I might add that if I think about it, an airway is 4 miles wide, so maybe the 4 mile safety zone is to help protect us bug smashers with barely working VOR's that may be a few degrees off. Don't ask me what 4 degrees off course at 60 miles equates to off airway distance. I agree with the comment earlier, that just because the VOT check is 4 degrees off on the 180/360 doesn't mean that the deviation on an actual airway is the same.

Cheers
 
Actually, and I could be wrong on this, but I think that is how a VOR indicator works (if it's off at 180, then its off all the way around... it's not like compass deviation). Generally what you're checking is the head alignment/resolver, not the actual receiver. And it's really the older style (and mostly cheaper) style VOR heads that go out of alignment.... I'm not an avionics tech, but that's my understanding... maybe someone around here would know more.

An airway is only 4.5 degrees wide beyond 50nm... so if you're VOR is off 4 degrees and it's a long airway, you're potentially really skirting the edge of protection...
 
I've been on a flight where nav 1 was -3 and nav2 was +4 so if we flew the airway with one needle centered, the other was nearly full deflection. Instead we decided to apply the correction and then we both had centered needles the rest of the flight. I recommend it!
 
I know this doesn't address the question, but if I were four degrees off on the TO, the next thing I'd do is check the FROM. Based on what that shows, make a judgment call from there.
 
Actually I think I was pretty clear. If you know where the center of the airway is located, you are obligated by regulation to fly down the center of that airway. The actual center of the airway isn't defined by your OBS radial, it is defined by a line through space.

Mountains don't move out of the way for people who are flying the "charted" radial number.
 
Lets put it this way: VOR error can be up to 6 degrees for an airborne checkpoint. For airway segments more than 51nm from a VOR defining the airway, the protection only goes out to 4.5 degrees. Again with the mountains not caring how well you matched your OBS to the charted OBS...
 
gotWXdagain said:
Lets put it this way: VOR error can be up to 6 degrees for an airborne checkpoint. For airway segments more than 51nm from a VOR defining the airway, the protection only goes out to 4.5 degrees. Again with the mountains not caring how well you matched your OBS to the charted OBS...
Click to expand...

Great points. But until the VOR indicator comes with a VOR correction card, I'm setting and flying the needle as charted (as long as the check is within limits).
 
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