Navigation Aids

VOR – Very high Omni-directional ranger-reliable ground based means of electronic navigation which enables a pilot to navigate \ without reference to the ground.

  • VHF so line of sight applies (108.0 – 117.95)
  • 360 different radials extending from the center each one on a specific degree of heading like the spokes of a wheel
  • Radial are close together at the station but far apart as you get far away, at 60 nm they are 1nm apart.

NAV flag means no usable signal being received

  • set turned off
  • VOR not transmitting
  • LOS interfered with
  • something wrong with the receiver

VOR Checks – to be Instrument current the VOR must be checked every 30 days.

  • VOT’s – test facilities that transmit on 180 (to) or 360 (from)
  • VOR Checkpoints – Ground or Airborne based, ground tolerance is +_ 4 Airborne +_ 6 consult A/FD.

OBS – Omni Bearing selector – is a course selector that allows the pilot to select any of the 360 magnetic courses to follow.

CDI – Course deviation Indicator – will tell you which way to fly to intercept a given course. If the heading and OBS are not in general agreement then you will get reverse sensing.

  • Fly 10 degrees per dot from selected OBS to get back on course.

To/From Indicator – Tells you whether you are going to or from the station

Teaching a VOR

  • How do you call FSS through a VOR?
  • Position check using 2 VORS
  • Not all VORS have a compass rose around them, hard to see
  • VOR tells you where the station is in relation to what you have set in the OBS

NDB – Non-directional Beacon – Ground unit that transmits on AM frequencies

  • In the airplane we use an ADF to receive the signal
  • The signal is in relation to the aircraft (ie 0 degrees is the nose, 180 the tail, 90 the right wing, and 270 the left wing)


  • Can pick up signals from great distances
  • will point to the direction of the wind
  • Relative bearing – the heading the needle is pointing to – RB = “relative bearing to the nose”
  • MH + RB = MB
  • Bird Dog

DME – Distance measuring Equipment

  • You can obtain slant range to VOR/DME, VORTAC
  • Sends out a paired pulse to a ground station, it times the response and displays it in NM.

GPS – Global Positioning System

  • Satellite based radio navigation, positioning and time transfer system
  • Accuracy within 100 meters
  • Not good enough for vertical navigation
  • RAIM – Receiver Autonomous Integrity Monitoring
    • You can not make an approach unless your receiver meets approach RAIM requirements

RNAV (Genre)

  • Area Navigation is enhanced navigational capability by computing the the aircrafts position, actual track, and ground speed.
  • Typical RNAV equipment gives distance, time, bearing, and cross track error.
  • Present Rnav includes INS, LORAN, VOR/DME, and GPS.