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Old July 12th 06, 08:26 PM posted to rec.aviation.ifr
Jim Macklin
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Posts: 2,070
Default who does VOR "calibration" for most accurate VOR approaches?

That's true. Even the 30 day rule was a compromise between
the needs of the still used tube radios and the solid state
radios. I have done ground checks at surveyed locations,
checks between two radios, had shops do a calibration and
done checks along an airway over a landmark. What I have
seen is that a poor antenna or a interference in the
airplane, such as a bad alternator, can cause problems.
Turn both VORs OFF and the needles will be centered, what
does that tell you? If the receiver is weak because of
antenna problems the needle sensitivity will be poor. If it
takes 15-20 degrees of knob turning to get full scale
deflection, the observation that the needles are within 4
degrees or 6 degrees of anything means very little, since it
is taking twice the standard deviation to move the needle.
A check within five miles of the VOR on the airport with a
VOT is legal, but check sensitivity. And check the system
along an airway at 30-50 miles every so often.


--
James H. Macklin
ATP,CFI,A&P

"RK Henry" wrote in message
news | On Wed, 12 Jul 2006 08:03:09 -0500, "Jim Macklin"
| wrote:
|
| Set the OBS to the published radial/course. In the old
days
| of vacuum tube radios, the tubes would change their
tuning
| as they got hotter and wore out. Thus the 30 day check
| rule. Modern solid state VOR are very stable and once
| adjusted are likely to stay within tolerance until they
| fail.
|
| Except that back then the rule required that the VOR check
be
| performed every 10 days. About 30 years ago, after
solid-state
| equipment became commonly available, the FAA liberalized
the rule to
| its present 30 day interval.
|
| RK Henry