Vor navigation and_tracking

Intercepting and Intercepting and Tracking VOR’sTracking VOR’s

Ideal for IFR StudentsIdeal for IFR Students

by Derek W Beckby Derek W BeckMay 2008 (revised Nov 2008)May 2008 (revised Nov 2008)

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ObjectiveObjective

Develop an understanding of how Develop an understanding of how to use VOR for navigation and to use VOR for navigation and

how to track along a VOR radialhow to track along a VOR radial

ContentContent• What is a VOR and How Does it Work?What is a VOR and How Does it Work?• Tuning and Identifying a VORTuning and Identifying a VOR• Flying to a VOR StationFlying to a VOR Station

– Station PassageStation Passage• Intercepting a VOR CourseIntercepting a VOR Course• Tracking a Course (Wind Correction)Tracking a Course (Wind Correction)• Reverse SensingReverse Sensing• VOR IntersectionsVOR Intersections• VOR FailuresVOR Failures• QuizQuiz

Why VOR’s?Why VOR’s?

• VOR’s create the VOR’s create the “highways in the sky” “highways in the sky” that, besides GPS, that, besides GPS, are the primary way are the primary way to fly in IFR conditionsto fly in IFR conditions– These “highways” are These “highways” are

called VOR Airways or called VOR Airways or Victor AirwaysVictor Airways

IFR Enroute Low Altitude ChartIFR Enroute Low Altitude ChartDepicting VOR “highways”Depicting VOR “highways”

What is a VOR?What is a VOR?

• It stands for VHF (Very High Frequency) It stands for VHF (Very High Frequency) Omnidirectional RangeOmnidirectional Range

• It’s a radio beacon on the ground that tells It’s a radio beacon on the ground that tells allows an aircraft to identify their location allows an aircraft to identify their location relative to the VORrelative to the VOR

Source: FAA-H-8083-15A Instrument Flying HandbookSource: FAA-H-8083-15A Instrument Flying Handbook

A typical VOR:A typical VOR:

Inside the AircraftInside the Aircraft

The airborne equipment includes the The airborne equipment includes the navigation side of the radio, the VOR navigation side of the radio, the VOR indicator (often two in an airplane), and an indicator (often two in an airplane), and an antenna for each VOR indicatorantenna for each VOR indicator

OBSOBS

NNAAVV

omnibearing selectoromnibearing selector

course deviation indicator (CDI)course deviation indicator (CDI)

TOTO

FRFR

How Does a VOR Work?How Does a VOR Work?Imagine a lighthouseImagine a lighthouse: Its beacon rotates, : Its beacon rotates,

but at North it flashes in all directions. If but at North it flashes in all directions. If you were to time between when you see you were to time between when you see the flash and when you see the beacon, the flash and when you see the beacon, you could calculate your position to it. you could calculate your position to it. (A VOR does the same thing, (A VOR does the same thing, but with radio waves.)but with radio waves.)

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How Does a VOR Work? How Does a VOR Work? (technical)(technical)

• It emits (2) two VHF radio waves, one It emits (2) two VHF radio waves, one unchanging wave in all directions (a reference unchanging wave in all directions (a reference for 360º), and a second variable wave, the for 360º), and a second variable wave, the phase of which changes as it rotatesphase of which changes as it rotates

• A VOR receiver inside an aircraft compares the A VOR receiver inside an aircraft compares the phase of the rotating beacon to the reference phase of the rotating beacon to the reference and determines which “radial” from the station and determines which “radial” from the station the aircraft is onthe aircraft is on

Tuning and Identifying VOR’sTuning and Identifying VOR’s• Get VOR information Get VOR information

from IFR and VFR charts, from IFR and VFR charts, Airport/Facilities Airport/Facilities Directory, etcDirectory, etc

• Put the VHF frequency Put the VHF frequency into the Nav side of the into the Nav side of the radio and click “IDENT”radio and click “IDENT”

• Listen to the Morse Code Listen to the Morse Code identifier, also depicted identifier, also depicted on charts (always confirm on charts (always confirm you have the VOR you you have the VOR you think)think)

VORVOR

Frequency Frequency & Morse & Morse Code IDCode ID

Using a VORUsing a VOR

Let’s go to the station…Let’s go to the station…

360º360º

090º090º

180º180º

270º270º

RadialsRadials– VOR radials emanate VOR radials emanate

(radiate) (radiate) FROMFROM the station the station– They are always FROM!!!!They are always FROM!!!!– They are NEVER to!They are NEVER to!– Imagine a bicycle wheel… Imagine a bicycle wheel…

the radials are the spokes, the radials are the spokes, coming FROM the centercoming FROM the center

– They radiate in all They radiate in all directionsdirections

– Radials based on Magnetic Radials based on Magnetic NorthNorth

– Since they converge at the Since they converge at the station, staying on course station, staying on course becomes more sensitive becomes more sensitive close to the VORclose to the VOR

360º360º

090º090º

180º180º

270º270º

Fly to a StationFly to a Station• Turn the OBS to center the Turn the OBS to center the

VOR’s “needle” (CDI)VOR’s “needle” (CDI)• Make sure it says “TO” the Make sure it says “TO” the

stationstation

HDGHDG

Inside our airplane:Inside our airplane:

OBSOBS

TOTO

360º360º

090º090º

180º180º

270º270º

Station PassageStation Passage• The “Cone of Confusion”, a The “Cone of Confusion”, a

zone of mixed signals just over zone of mixed signals just over the station, gives erratic the station, gives erratic readingsreadings– Stay on your heading during Stay on your heading during

the cone of confusion!the cone of confusion!• Look for the “TO” to change to Look for the “TO” to change to

a “FROM”a “FROM”

HDGHDGOBSOBS

NNAAVV TOTO

FRFR

360º360º

090º090º

180º180º

270º270º

After PassageAfter Passage• Notice it now says “FROM” the Notice it now says “FROM” the

stationstation• You are now flying on the 360º You are now flying on the 360º

radial FROM the stationradial FROM the station

HDGHDG

Inside our airplane:Inside our airplane:

OBSOBS

FRFR

360º360º

180º180º

Keep the CDI CenteredKeep the CDI Centered

• Needle centered = on courseNeedle centered = on course• Needle to the right = course to Needle to the right = course to

the right (& vice versa)the right (& vice versa)• Turn to the needle to stay on Turn to the needle to stay on

coursecourse• Full deflection: 10-12º off Full deflection: 10-12º off

FRFR

course to the rightcourse to the right course to the leftcourse to the lefton courseon course

FRFR FRFR

360º360º

180º180º

Heading Doesn’t Matter!Heading Doesn’t Matter!

• VOR’s are “dumb” instrumentsVOR’s are “dumb” instruments• VOR assumes you are going VOR assumes you are going

same direction as the coursesame direction as the course• Airplane “A” is still left of 360 Airplane “A” is still left of 360

course; “B” is still on the 360 course; “B” is still on the 360 course (momentarily)course (momentarily)

FRFR

course to the rightcourse to the right course to the leftcourse to the lefton courseon course

AA BBFRFR FRFR

090º

Inside our airplane:

Intercepting a VOR Course• Step 1: Set desired VOR

course on VOR using OBS– Let’s intercept 090º– Be sure to tune and ID VOR

first!

Turn OBS

270º

OBSOBS

TOTO

HDGHDG

HDGHDG

OBS

OBS

TOTO

Intercepting a VOR CourseIntercepting a VOR Course• Step 2: Turn aircraft to a same Step 2: Turn aircraft to a same

desired coursedesired course– Heading should match VOR Heading should match VOR

course – you will parallel course – you will parallel coursecourse

270º270º 090º

HDGHDG

OBS

OBS

TOTO

Intercepting a VOR CourseIntercepting a VOR Course• Step 3: Select an intercept Step 3: Select an intercept

angle to get on course (to angle to get on course (to center needle), 30-45º is bestcenter needle), 30-45º is best– Notice VOR needle is left, so Notice VOR needle is left, so

your course is to the leftyour course is to the left

270º270º 090º

HDGHDG

OBS

OBS

TOTO

Intercepting a VOR CourseIntercepting a VOR Course• Step 4: Wait for VOR needle to Step 4: Wait for VOR needle to

centercenter– As you near the course, the As you near the course, the

needle will come in towards needle will come in towards centercenter

270º270º 090º

HDGHDG

OBS

OBS

TOTO

Intercepting a VOR CourseIntercepting a VOR Course• Step 5: Turn to desired course Step 5: Turn to desired course

as needle centersas needle centers– Try to lead the turn as the Try to lead the turn as the

needle centers to not needle centers to not overshoot the courseovershoot the course

270º270º 090º

HDGHDG

OBS

OBS

TOTO

Tracking: Fighting the WindTracking: Fighting the Wind• Step 1: Turn 20º towards Step 1: Turn 20º towards

course to re-interceptcourse to re-intercept

090º090º270º270º

WIN

DW

IND

HDGHDG

OBS

OBS

TOTO

Tracking: Staying on CourseTracking: Staying on Course• Step 2: Wait until the needle is Step 2: Wait until the needle is

re-centeredre-centered

090º090º270º270º

WIN

DW

IND

HDGHDG

OBS

OBS

TOTO

Tracking: Staying on CourseTracking: Staying on Course• Step 3: once needle is re-Step 3: once needle is re-

centered, turn heading back centered, turn heading back half way of correction angle half way of correction angle (10º)(10º)

• Tweak with smaller corrections Tweak with smaller corrections as necessary to stay on course as necessary to stay on course (called “bracketing”)(called “bracketing”)090º090º270º270º

WIN

DW

IND

net resultnet result

HDGHDG

OBS

OBS

TOTO

A WarningA Warning• Notice the airplane isn’t on the Notice the airplane isn’t on the

090º radial? It’s on 270º!090º radial? It’s on 270º!• But radials are But radials are FROMFROM the the

station! station! • We are on the 270º radial…We are on the 270º radial…• But to go TO the station, we But to go TO the station, we

must use the reciprocal heading must use the reciprocal heading (090º)(090º)

090º090º270º270º

HDGHDGOBS

OBS

The Danger:The Danger: Reverse Sensing Reverse Sensing• If we put the 270 course in the If we put the 270 course in the

VOR, what would happen?VOR, what would happen?• VOR’s are dumb! It assumes VOR’s are dumb! It assumes

you are going 270ºyou are going 270º• The flag says “FROM” even The flag says “FROM” even

though you are going TO!though you are going TO!• Remember: Heading doesn’t Remember: Heading doesn’t

matter to a VOR!matter to a VOR!

FRFR

090º090º270º270º

HDGHDGOBS

OBS

The Danger:The Danger: Reverse Sensing Reverse Sensing• If you are off course when If you are off course when

reverse sensing… The needle reverse sensing… The needle gives opposite indicationsgives opposite indications

• This airplane has the course to This airplane has the course to the right, but the VOR shows it the right, but the VOR shows it off to the left!off to the left!– Not to mention that “FROM” Not to mention that “FROM”

flag when going TO the VOR!flag when going TO the VOR!

FRFR

090º090º270º270º

HDGHDGOBS

OBS

AvoidAvoid Reverse Sensing Reverse Sensing• Is reverse sensing confusing? Is reverse sensing confusing?

That’s why you should avoid it!That’s why you should avoid it!• Insure the VOR course Insure the VOR course

selected selected generallygenerally matches the matches the heading you are flyingheading you are flying

FRFR

090º090º270º270º

HDGHDGOBS

OBS

Tricky Tricky WordingWording• If told “track the 270º radial to If told “track the 270º radial to

the station…”the station…”• Watch out! Watch out! Radials ONLY go Radials ONLY go

FROM the station!!! FROM the station!!! • Instead, track the reciprocal Instead, track the reciprocal

heading (notice you are on heading (notice you are on 270º but tracking 090º?)270º but tracking 090º?)

FRFR

090º090º270º270º

No!No!

No!No!

Finding IntersectionsFinding Intersections• An VOR intersection is a point An VOR intersection is a point

where a radial from one VOR where a radial from one VOR crosses a radial from a second crosses a radial from a second VORVOR

090º090º270º270º

TOTO

OBS

OBS

TOTO

OBS

OBS

Heading VOR 1 VOR 2Heading VOR 1 VOR 2

210º210º

030º030º

HDGHDG

Finding IntersectionsFinding Intersections• Step 1: Set VOR 2 to desired Step 1: Set VOR 2 to desired

intersecting radial intersecting radial – In this case: 030º In this case: 030º – Be sure to tune and ID for Be sure to tune and ID for

VOR 2VOR 2

TOTO

OBSOBS

FRFR

OBS

OBS


HDGHDG

090º090º270º270º

210º210º

030º030º

Finding IntersectionsFinding Intersections• Step 2: Wait for VOR 2’s Step 2: Wait for VOR 2’s

needle to centerneedle to center– It’s recommended to use VOR It’s recommended to use VOR

1 for the course you are on, 1 for the course you are on, VOR 2 for intersectionsVOR 2 for intersections

090º090º270º270º

TOTO

OBSOBS

FRFR

OBS

OBS


210º210º

030º030º

HDGHDG

Finding Intersections Made EasyFinding Intersections Made Easy• A Trick: if we use the heading (East or A Trick: if we use the heading (East or

090º on the heading indicator) and find 090º on the heading indicator) and find this on the VOR 2 dial, 090 on VOR 2 this on the VOR 2 dial, 090 on VOR 2 is the same side as the CDI needle: is the same side as the CDI needle: “Same Side Safe” (you haven’t “Same Side Safe” (you haven’t reached the intersection yet)reached the intersection yet)

• If the CDI is on the opposite side, If the CDI is on the opposite side, you’ve passed the intersection.you’ve passed the intersection.

270º270º

TOTO

OBSOBS

FRFR

OBS

OBS


210º210º

030º030º

HDGHDG

If CDI is same side as heading, you If CDI is same side as heading, you haven’t reached the intersection haven’t reached the intersection

(“Same Side Safe”)(“Same Side Safe”)

Finding IntersectionsFinding Intersections• Once the VOR 2 needle is Once the VOR 2 needle is

centered, you are at the centered, you are at the intersectionintersection

090º090º270º270º

TOTO

OBSOBS

FRFR

OBS

OBS


210º210º

030º030º

HDGHDG

VOR FailureVOR Failure• Tune and ID but no ID signal? Tune and ID but no ID signal?

– The VOR station may be The VOR station may be inoperative (check NOTAMS)inoperative (check NOTAMS)

• VOR flag on the indicator? VOR flag on the indicator? – Station or indicator may be Station or indicator may be

inoperativeinoperative• VOR’s must be checked for VOR’s must be checked for

accuracy every 30 days for accuracy every 30 days for use in IFR flight use in IFR flight – see 14 CFR 91.171 for detailssee 14 CFR 91.171 for details

OBSOBS

NNAAVV

FRFR

Quiz Time!Quiz Time!

Quiz #1Quiz #1Where is this aircraft relative to the VOR?Where is this aircraft relative to the VOR?

TOTO

OBS

OBS

Heading VOR 1Heading VOR 1

HDGHDG


TOTO

OBS

OBS


HDGHDG

225º225º

045º045º


OBSOBS


HDGHDG

FRFR


OBSOBS


HDGHDG

330º330º

150º150º

FRFR


TOTO

OBS

OBS


HDGHDG


TOTO

OBS

OBS


HDGHDG

210º210º

030º030º


TOTO

OBS OBS


HDGHDG

FRFR


TOTO

OBS OBS


HDGHDG

315º315º

135º135º

FRFR

TO side of 135ºTO side of 135º

FROM side of 135ºFROM side of 135º


TOTO

OBSOBS


HDGHDG


TOTO

OBSOBS


HDGHDG 110º110º

290º290º

Reverse SensingReverse Sensing

Further ReadingFurther Reading

• FAA-H-8083-15A Instrument Flying Handbook Chapter 7

• FAA-H-8083-25 Pilot’s Handbook of Aeronautical Knowledge Chapter 14

Business

Vor navigation and_tracking