Intercepting & Tracking
Radial intercepting and tracking establish the airplane on a predetermine radial and to track it to a location, thereby aiding in navigation.
Introduction to Intercepting & Tracking
- Radial intercepts and tracking for both VORs and TACANs are flown identically
- Their purpose is to establish the airplane on a predetermine radial and to track it to a location, thereby aiding in navigation
- once established, pilots must then be able to make necessary corrections for the effects of wind
WARNING:
All procedures are GENERALIZED.
Use the Pilot Operating Handbook (POH) procedures for specific aircraft performance and limitations.
and/or current Standard Operating Procedures (SOPs).
Intercepting & Tracking Key Highlights
- VOR and TACAN radial intercept and tracking procedures allow pilots to navigate accurately using ground-based navigation systems.
- VOR systems provide azimuth guidance through radials extending outward from the navigation station.
- TACAN systems provide military navigation capability with azimuth and distance information similar to VOR/DME functionality.
- Intercepting a radial requires selecting the desired course, determining aircraft position, and choosing an appropriate intercept angle.
- Wind correction techniques are necessary to maintain accurate course tracking and prevent drift from the selected radial.
- Course deviation indicators and heading adjustments help pilots maintain precise navigation alignment during tracking operations.
- Reverse sensing can occur if the selected course or aircraft orientation is interpreted incorrectly.
- Pilots should identify navigation stations positively using Morse code or approved identification methods before use.
- Modern RNAV and GPS systems supplement traditional VOR and TACAN navigation but understanding ground-based systems remains important.
- Understanding VOR and TACAN radial intercept and tracking improves navigation proficiency, situational awareness, and overall flight safety.
Introduction to Intercepting & Tracking
- Homing is flying the aircraft on any heading required to keep the needle pointing directly to the 0° Relative Bearing (RB) position.
- The Automatic Direction Finder (ADF) may be used to "home" in on a station.
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Homing Procedure
- Tune the station, identify the Morse code signal and identify the station, as appropriate.
- Turn the aircraft to bring the ADF azimuth needle to the 0° releative bearing (RB) position (straight up and down).
- Turns should be made using the heading indicator.
- When the turn is complete, check the ADF needle and make small corrections as necessary to keep the needle straight up and down (RB of 0°).
- Small heading corrections are then made to zero the ADF needle.
- If there is no wind, the aircraft homes to the station on a direct track over the ground.
- With a crosswind, the aircraft follows a circuitous path to the station on the downwind side of the direct track to the station.
VOR & TACAN Radial Intercept Procedure
- Tune the station frequency and verify the station's Morse Code identifier
- Check the heading indicator with the magnetic compass
- Reset as necessary
- Turn the airplane to a heading to parallel the desired course, in the sae direction as the course to be flown
- With the Omni Bearing Selector (OBS), center the Course Deviation Indicator (CDI) with a TO flag indication (inbound), or a FROM flag indication (outbound) as appropriate
- Determine the difference between the radial to be intercepted and the radial presently on
- Double the difference to determine the interception angle
- May not be less than 20°, nor more than 90°
- Since the distance between radials varies with distance from the station (at 60 NM 1° between radials = 1 nm, 30 NM, 1° = 0.5 NM, etc.), the amount of intercept heading used must vary accordingly to prevent overshooting the desired course
- Rotate the OBS to select the desired radial ("FROM" Flag), or the course ("TO" Flag)
- Turn to the intercept heading determined and hold the heading constant until the CDI begins to center
- As the CDI begins to center, begin turning to the heading corresponding to the radial or course selected
- Track the radial (outbound) or course (inbound), as appropriate
- As proficiency increases, steps 3 and 4 may be eliminated
- Once the radial has been intercepted, proceed with VOR/TACAN Radial Tracking procedures
VOR & TACAN Radial Tracking Procedure
- After the course has been intercepted, maintain the heading that corresponds to the course selected
- If the CDI should move off center, re-intercept by beginning with a 20° change (intercept angle) in heading (intercept heading) toward the deflection of the CDI
- Maintain the intercept heading until the CDI re-centers, and then turn back to a new course heading by taking out 1/2 of the intercept angle
- For example, the airplane has drifted to the right of the 090° radial (outbound). To re-intercept the radial, a left turn is made to a heading of 070°. When the CDI re-centers, a right turn is made to maintain a new Course Heading of 080° (10° Wind Correction Angle)
- If the CDI should move off center, re-intercept by beginning with a 10° change in heading (intercept heading) toward the deflection of the CDI
- Maintain the intercept heading until the CDI re-centers, and then turn back to a new course heading by taking out 1/2 of the intercept angle
- For example, The airplane has drifted again to the right of the 090° radial (outbound). To re-intercept the radial, a left turn is made to a heading of 070° (10° change). When the CDI re-centers, a right turn is made to maintain a new Course Heading of 075° (5° change, 15° Wind Correction Angle now total)
- Wind conditions may require the use of intercept angles greater than 20° to change the direction of the CDI deflection however, the "bracketing" procedures above are still applicable
- Consider setting the heading bug to the heading to be flown so as to maintain the wind correction angle and therefore track
- Deviations:
- Consider what full-scale deflection means in terms of distance for the mode of flight the aircraft is in (enroute, terminal, etc.) or sensitivity relative to distance from a navigation station to understand how far off you are before inputting too much or too little of a correct
- Referencing a cross-track error (XTK) from the avionics or EFB, if available, to better guage your deviation
Airman Certification Standards
Intercepting & Tracking Knowledge Check
Intercepting & Tracking Conclusion
- Distinguishing the meaning of FROM and TO is important to avoid reverse sensing
- We fly a course TO, and intercept radials FROM
- Although these procedures are largely written for radio frequency NAVAIDs, GPS procedures are very similar
- Consider actual versus realized performance when doing any performance calculations
- Consider practicing maneuvers on a flight simulator to introduce yourself to maneuvers or knock off rust
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Intercepting & Tracking References
- Federal Aviation Administration - Pilot/Controller Glossary.
- Instrument Flying Handbook