The uses of a VORVOR EquipmentHow VOR work?Advantages VOR Disadvantages of VOR

Introduction

VOR, short for VHF Omni-directional Radio Range, is a type of radio navigation system for aircraft. VOR is the primary navigational aid (NAVAID) used by civil aviation in the National Airspace System (NAS).

The uses of a VOR

Marking the BEGINNING, the END and CENTER-LINE of airways. In short word, VOR guide an aircraft from point A to point B.As a let-down aid at airport based on procedures.As a holding point for aircraftAs a source of en-route navigational position lines.

VOR EquipmentVOR Equipment

Ground VOR transmitterAircraft’s antenna:

For low-speed a/c the antenna is whip type fitted on the fuselage.For high-speed aircraft it is a blade type on vertical tail.

Aircraft’s VOR receiver in the cockpit:

Ground VOR transmitterGround VOR transmitter

VOR station for broadcast the signal

Ground VOR transmitterGround VOR transmitterThe VOR ground station is oriented to magnetic north.It produces 360° radials/tracks at 1° spacing.These 360 bearings are known as RADIALSWhen DME is installed with the VOR, it is referred to as a VOR/DME. When military tactical air navigation (TACAN) equipment is installed with the VOR, it is known as a VORTAC.VOR ground installations are strategically located along air routes and airport to ensure continuity of guidance.

PRINCIPLE OPERATION OF VOR

How VOR worksHow VOR worksVOR station provide BEARING information relative to the aircraft position.VOR stations broadcasts a VHF signal between 108-117.95 MHz with adequate power to provide coverage.The basic principle of operation of the VOR is very simple, VOR stations transmit 2 signals at the same timeFirst signal is transmitted by single antenna in the center, this signal is constant in all direction and contains station's identifier information given in MORSE CODE. For example, KLIA airport has a VOR known as VKL-Victor Kilo Lima.While, the second signals are transmitted by other antennas that circling around the single antenna.

When aircraft receives these two signals, an aircraft VOR receiver will measure the phase angle different between these two signals.This phase angle different is translated as the magnetic BEARING which tell the pilot the aircraft direction to the VOR station.This bearing angle also known as RADIALS.

090

045

135

180

225

270

315

360

The Principle of the VORThe Principle of the VORMagnetic North

135º

Aircraft’s VOR receiver

VOR receiver in aircraft to receive and interpret the signal. Show the bearing/direction of the aircraft from the VOR station.

VOR indicatorVOR indicator

Omnibearing Selector (OBS). Course deviation indicator (CDI).

The needle centers when the aircraft is on the selected radial.

TO/FROM indicator. Shows whether the selected course will take the aircraft TO or FROM the station.

Flags:The device that indicates a usable or an unreliable signal may be an “OFF” flag.

Omni bearing selector

Omni bearing selector

To/From indicator.

ReceiverCourse Deviation

Indicator (CDI)

The VOR is the most common navigation instrument presently on aircraft panels.Accurate:

The accuracy of course alignment of the VOR is excellent, being generally plus or minus 1 degree.

Reliable:Space wave transmission, travels in straight line, not effect by interference, not affected by sky waves, can be used day and nighr.

Provide multiple number of route ‘towards’ or away from each station.

These routes are like invisible highways , which the pilot can navigate to @ away from any location.

Advantages of VOR

The VOR enables a pilot to select, identify, and locate a line of position from a particular VOR beacon. The following information can be obtained:

The magnetic bearing of the aircraft from the VOR beaconThe position of the aircraft

The range of VOR signal is limited to ‘line of sight’ reception. Thus, the range depends on:

Aircraft’s Altitude - minimum 1000 ft to receive the VOR signalThe ground VOR transmitter height- The lower the transmitter the lower the range.The nearest mountains and buildings cause VOR bearings to be stopped and interrupted.

Other disadvantages is VOR equipments are costly to maintain.

VOR Test (VOT) Facility

VOR accuracy must be calibrated/checked for every months. One acceptable way to check VOR accuracy is with a VOR (VOT) Test FacilityA VOT is a low-power Omni station and it transmits only a single radial, the 360° radial. To calibrate a VOR, the pilot tunes in the VOT frequency while on the ground.

Exercise

Define VOR and give two uses of VOR.

Explain how VOR works

Explain 2 advantages of VOR

Explain 2 disadvantages of VOR