VOR (Very High Frequency Omnidirectional Range) Station
A VOR (Very High Frequency Omnidirectional Range) Station is a ground-based radio navigation facility operating in the VHF band (108.0–117.95 MHz) that transmits bearing information to aircraft receivers in all directions simultaneously. VOR is the primary en route navigation system in Canadian airspace, forming the backbone of the IFR airway structure.
How VOR Works
A VOR transmits two signals simultaneously: a reference phase signal (constant in all directions) and a variable phase signal (whose phase varies with direction). The airborne VOR receiver compares the phase difference between these two signals to determine the magnetic bearing FROM the station — the radial. The OBS (Omni Bearing Selector) is turned to select the desired course.
VOR Receiver and CDI
- Tune the VOR frequency on the NAV receiver
- Identify the station by Morse code (mandatory before use)
- Set the OBS to the desired radial or course
- Read the CDI for deviation from the selected course
- TO flag indicates flying toward the station; FROM indicates flying away
VOR Accuracy and Limitations
- Accuracy: ±1° to ±2° from the centre of published airways
- Line-of-sight: range limited by altitude and terrain — check the MEA for navigation guarantee
- Cone of confusion: directly above the VOR, signals are unreliable — brief needle fluctuation on overhead passage is normal
- Scalloping: multipath reflections from terrain or buildings can cause needle oscillation near the station
On the TC Written Exam
VOR navigation is extensively tested at both PPL and CPL levels. Know: how to tune, identify, and use the VOR; TO/FROM flag interpretation; CDI deflection direction; cone of confusion; the difference between radial and bearing.