Definition
An accuracy check of an aircraft's VOR navigation equipment performed by tuning both VOR receivers to the same VOR station, centering the course deviation indicator on each, and comparing the two indicated bearings. The maximum permissible variation between the two indicated bearings is 4 degrees.
Plain English
A way to confirm your two onboard navigation receivers are accurate by tuning them both to the same ground station and checking that they agree within 4 degrees of each other.
Context Anchor
Used when checking whether installed VOR navigation equipment is accurate enough for instrument flight, especially before relying on it in the airplane or logging the required VOR check.
Derivation
"Dual" simply means two, and refers to the aircraft having two independent VOR receivers. The check uses both receivers against a single station so that one receiver acts as a cross-reference for the other.
Why Pilots Care
Confirms both VOR receivers are accurate enough to use for instrument navigation, reducing the risk of heading or course errors in IMC.
Grounding Statement
Both VOR receivers are listening to the same ground station, so their displayed directions should nearly match.
Intuition Check
Dual VOR Check does not mean performing two separate VOR checks. It means comparing two VOR receivers against the same VOR station at the same time or under the same check conditions.
Example Sentence 1
Before departing on the IFR flight, the pilot performed a dual VOR check by tuning both receivers to the local VOR and confirming the indicated bearings agreed within 4 degrees.
Example Sentence 2
A dual VOR check that showed more than a 4-degree difference required the pilot to troubleshoot the radios before flying IFR.