Definition
VOR/NDB refers to two ground-based radio navigation aids used by aircraft to determine bearing to or from a fixed station. A VOR transmits VHF signals that allow the aircraft's receiver to display the radial (magnetic bearing) the aircraft is on relative to the station. An NDB transmits a low or medium frequency non-directional signal that an aircraft's Automatic Direction Finder (ADF) receiver uses to indicate the relative bearing to the station. On an electronic flight display, VOR and NDB information is typically presented on the Horizontal Situation Indicator (HSI) or a bearing pointer, allowing the pilot to track courses, intercept radials, or home to the station.
Plain English
Two types of ground radio stations that an aircraft can tune in to figure out which direction the station is from the aircraft. The VOR is the more precise, modern one; the NDB is older and simpler. Pilots use them to follow set paths through the sky or to fly toward a specific point.
Context Anchor
Seen on instrument displays and navigation pages when selecting or identifying a radio navigation source.
Derivation
VOR stands for VHF Omnidirectional Range — 'omnidirectional' (Latin omnis, 'all' + 'directional') because the station transmits usable signals in every direction around it, not just along one path. NDB stands for Non-Directional Beacon — 'non-directional' because the signal radiates outward equally in all directions; the aircraft receiver determines direction, not the beacon itself.
Why Pilots Care
These aids remain required or authorized for many IFR procedures and provide independent position information when GPS is lost or restricted.
Intuition Check
VOR/NDB does not mean one combined navigation system. It means the display or discussion may be referring to either VOR information or NDB information.
Example Sentence 1
After takeoff, the pilot tuned the VOR to track the 270 radial outbound while monitoring the nearby NDB on the ADF as a cross-check.
Example Sentence 2
During partial-panel practice the instructor covered the GPS and required the student to navigate solely with VOR/NDB indications.