Slide 1

VOR Navigation

Richard Champion1VOR NavigationAimTo learn how to use VHF Omnidirectional Range (VOR) equipment as an aid to visual navigation.ObjectiveBy the end of this briefing, you should be able to tune and identify VORs, intercept and track a VOR radial, fix your position using two VORs, use a VOR to avoid controlled airspace and accurately interpret VOR indications.Airmanship Lookout (esp near a beacon). Accurate navigation. Avoiding airspace bustsAgendaThe VORThe Course Deviation Indicator (CDI)Tune and identifyIntercept and trackAdjusting for windPosition fixSetting a guard railInterpretationSummary

2The VOR TransmitterDepicted like this on charts:-

The Transmitter broadcasts two signals:- A constant phase signal which is identical in all directionsA reference signal with a varying phase, depending on direction from the beacon.Equipment on the aircraft measures the phase difference between the two signals and interprets this as a radial from the beacon.These radials can be pictured as spokes radiating from the centre, each spoke representing a different QDR (magnetic bearing from the station). VORs are oriented with Magnetic North.VHF reception is line of sight. Maximum range will depend on the Altitude of the receiving aircraft.A 3 character Morse Code identifier is also broadcast.VORs are often co-located with Distant Measuring Equipment (DME) but the systems are independent.

3

TOFMThe Course Deviation Indicator (CDI)Omni Bearing SelectorUse to select radialCourse Deviation NeedleShows how far off selected radial you areThe Selected Radial is shown hereTO flag. Indicates that the selected bearing is TO the VORNB This does NOT mean that the aircraft is moving towards the VORFM flag. Indicates that the selected bearing is FROM the VORAgain, this does NOT mean that the aircraft is flying away from the VORDeviation scale. 2 Degrees per markOBS

4CDIs come in all shapes and sizes

Katana DA20

Cessna 172Cessna 1725Select, Tune and Identify

Select appropriate VOR from chartNote the frequency Note the IdentWrite Morse code Ident outTune Nav box standby FrequencyFlip flop to ActiveListen to Morse Ident

BIG115.100

112.35112.35NAV 1Pull Ident115.10115.10

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TOFMIntercept and Track a VOR radial

Current position: Approaching Bough BeechHeading 100On 160 radial from BIGSelect the140radial on the CDITurn right 10 to establish a 30 intercept angle. Fly towards the radialObserve the CDI needle moving toward the centre.Anticipate interception by a few degrees(4 if close/fast, 2 if far/slow)Turn onto 140 (or wind adjusted heading if known).

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FMAdjusting for WindUse your prior knowledge of the wind to estimate a wind correction angle.If in doubt, use 5 into wind as a starting point.Adjust heading by estimated wind correction angle.Continue flight, monitor CDI needle. If CDI needle moves, adjust heading sufficiently to stop further movement. Note new heading.Re-acquire the radial by centring the needle using 5 degree heading changes. Return to wind adjusted headingMonitor and adjust as required.

230/158Setting a Guard RailTo avoid infringing Gatwick Airspace:-Select the 270 radial from MAY2. Tune and Identify MAY, Set 270 on CDI3. Monitor CDI. Maintain Fly Right Signal

TOFMOBS

123.45123.45NAV 1Pull Ident117.90117.90

9Position Fix

123.45123.45NAV 1Pull Ident115.10115.10

TOFMOBS

117.30117.30 Enter first VOR frequency2. Flip Flop to active3. Listen to Morse IDTwist OBS until needle is centred with FM flag5. Draw Radial on chart6. Repeat with second VOR

10FInterpreting the CDI

117.90123.45NAV 1Pull Ident

TOOBS

ABCA, B or C?AnswerB060 TO11FInterpreting the CDI

117.90123.45NAV 1Pull Ident

FMOBS

ABCA, B or C?AnswerC

12FInterpreting the CDI

117.90123.45NAV 1Pull Ident

TOOBS

ABCA, B or C?AnswerA130 TO13SummaryWe have learned:-What a VOR isWhat the CDI doesHow to Tune and Identify a VORHow to intercept and track a radial to or from a VORHow to fix your positionHow to set a guard rail to keep you out side of controlled airspace or hazardHow to interpret what the CDI is telling us14