Definition
An allowable VOR signal irregularity that causes the course deviation indicator (CDI) needle or aircraft heading to fluctuate slightly while tracking a VOR radial, even when the aircraft is flown precisely. Under FAA standards, a small amount of course roughness is accepted as a normal characteristic of the VOR signal and is not considered a station malfunction.
Plain English
Small wiggles or jitters in the VOR needle or aircraft heading that show up even when you're flying the radial accurately. A little bit is normal and doesn't mean the equipment is broken.
Context Anchor
Seen in VOR accuracy discussions when deciding whether a VOR indication is stable enough to trust for navigation.
Derivation
‘Roughness’ here borrows from the everyday sense of a surface that isn’t smooth. The VOR signal is described the same way: instead of a perfectly steady course line, the signal has small bumps in it.
Why Pilots Care
It reduces the reliability of VOR course guidance and may require switching to another aid or increasing altitude.
Grounding Statement
Course roughness shows up as unexpected needle movement when the airplane is otherwise being held steady.
Intuition Check
Do not assume course roughness means rough air or a physically rough route. Here it means an uneven or unstable VOR course indication.
Example Sentence 1
The instructor pointed out that the slight CDI wobble was just course roughness, not a reason to re-tune the VOR.
Example Sentence 2
Course roughness was noted during the VOR accuracy check near mountainous terrain.