Definition
A pre-departure verification of an aircraft's VOR receiver to confirm it is displaying course information within allowable tolerance. Required by 14 CFR 91.171 for flight under IFR using VOR navigation, the check must be performed within the preceding 30 days using one of several approved methods: a VOT (VOR Test Facility), a designated ground or airborne checkpoint, comparison between dual VOR receivers, or a check against a published airway. Permitted error varies by method, generally ±4° for ground checks and ±6° for airborne checks. The date, place, bearing error, and pilot's signature must be entered in the aircraft logbook or other reliable record.
Plain English
Before flying on instruments using VOR, the pilot must test the VOR equipment to make sure it is pointing accurately. There are several approved ways to do this, and the result has to be written down with the date, location, error found, and the pilot's signature.
Context Anchor
Seen during instrument preflight planning, cockpit navigation checks, and discussions of using ground-based navigation aids for instrument flight.
Derivation
NAVAID is short for 'navigational aid' — any ground-based facility that provides signals for aircraft navigation. 'Accuracy check' is plain English: a check that the equipment is accurate. Knowing this reminds the pilot that the test is about the airborne receiver's ability to read the ground signal correctly, not the ground station itself.
Why Pilots Care
Confirms the navigation signal meets required accuracy so the pilot can safely follow instrument procedures without position error.
Intuition Check
Do not assume that receiving or identifying a navigation aid means it is accurate. The accuracy check confirms that the indication itself is within the allowed limits.
Example Sentence 1
Before filing IFR, the pilot taxied to the VOT on the ramp and performed a NAVAID accuracy check, recording the result in the aircraft logbook.
Example Sentence 2
During the approach briefing the crew noted the requirement to perform a NAVAID accuracy check on the VOR prior to intercepting the final approach course.