VOR Discrepancy
Thread Starter
Joined: Jun 2003
Posts: 3
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From: Cloudcuckooland
VOR Discrepancy
My light aircraft (public register) is fitted with 2 VOR's which were checked by a maintenance company on a recent Star Annual (at great expense!).
When I subsequently flew the aircraft after release to service, I noticed about 5 degrees variation between the VOR's when set to the same radial. When I questioned this with the company concerned they stated that variation is permissable up to five 5 degrees for VFR anyway.
As 5 degrees error is more than enough to take me where I don't want to be, I wonderered if any of you engineers out there could enlighten me to the rules in this area.
Questions: Are they telling me the truth?
Why would I want to use VOR for VFR anyway?
Which one (if any) should I trust?
Thanks
When I subsequently flew the aircraft after release to service, I noticed about 5 degrees variation between the VOR's when set to the same radial. When I questioned this with the company concerned they stated that variation is permissable up to five 5 degrees for VFR anyway.
As 5 degrees error is more than enough to take me where I don't want to be, I wonderered if any of you engineers out there could enlighten me to the rules in this area.
Questions: Are they telling me the truth?
Why would I want to use VOR for VFR anyway?
Which one (if any) should I trust?
Thanks
Joined: Oct 2002
Posts: 92
Likes: 0
From: Dubai, UAE
When the engineer carries out the annual radio inspection, part of the job is to check the accuracy of the VOR of course.
The tech uses a piece of equipment that generates known radial's and he/she adjusts the course knob until the deviation bar is in the centre. It's a JAR-145 requirement that they then record the deviation error even if its zero.
JAR-145 states that if you carry out an aircraft task that has a measurable result, then the result must be recorded. Even if they are not a JAR-145 organisation they should still record the result if they are worth their salt. Why not ask for the test results? Maybe one VOR is accurate and the other one needs a 'tweak'. Maybe they are both only 2.5° apart and this is acceptable to you. Either way you will know what you're dealing with.
Regards
The Doc
The tech uses a piece of equipment that generates known radial's and he/she adjusts the course knob until the deviation bar is in the centre. It's a JAR-145 requirement that they then record the deviation error even if its zero.
JAR-145 states that if you carry out an aircraft task that has a measurable result, then the result must be recorded. Even if they are not a JAR-145 organisation they should still record the result if they are worth their salt. Why not ask for the test results? Maybe one VOR is accurate and the other one needs a 'tweak'. Maybe they are both only 2.5° apart and this is acceptable to you. Either way you will know what you're dealing with.
Regards
The Doc
