VOR Navigation

VOR

  • Four course radio range
  • VOR: Very High Frequency Omni Range

It emits 360 radials

nav radios drive indicators on the panel

the indicator is called OBI: Omni Bearing Indicator, it has many  components, like OBS: Omni Bearing Selector, the needle in the center is a CDI: Course Deviation Indicator it represents the course line or radial, the flag gives us the status of the CDI

  • VHF OMNI RANGE
    • VOR
    • VORTAC (transmits distance info if aircraft equipped)
    • VOR-DME (transmits distance info if aircraft equipped)

The blue box on the sectional chart indicate the VOR frequencies

Heading & Bearing are the same when the airplane is headed toward the VOR, but it changes when the airplane is flying away from the station where bearing is heading + 180deg.

Radial: it starts at the station and extends outward.

VORs are aligned to magnetic north

We can use radials to help define our position.

Bearing does not include wind correction unlike heading

Practical use:

Where we are?

  1. from the chart look up the frequency in the blue box
  2. turn OBS to get “FROM” flag and center the CDI
  3. read the radial (ex: 235)

Fly to station?

  1. turn OBS to get “TO” flag and center the CDI
  2. read the radial

if we are on 250 heading with “TO” flag and then we pass the station, the VOR will detect that we are on a 250 radial and switch the flag to “FROM”

In a “FROM” configuration the wind blows us away from the course. You turn the airplane toward the needle (aircraft is doughnut circle in the center)

In a “TO” configuration the wind blows us away from the course. You turn the airplane toward the needle (aircraft is doughnut circle in the center)

Reverse Sensing: Flag differs from our motion relative to the station

Ex: if you forget to set your VOR back to the “TO” flag when flying to the station, then you are flying to the station with a “FROM” flag, so the needle move toward the opposite direction if you’re trying to fly toward the needle to get back on course you will keep getting further away.

  • When flying toward the station, have a “TO” flag
  • When flying away from the station, have a “FROM” flag

VOR instruments must be tested for accuracy by the pilot every 30 days.