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CFI Instrument Practical Test Standards, FAA-S-8081-9B, June 2001

VII. Navigation Systems

A. Intercepting and Tracking Navigational Systems and DME Arcs

To determine that the applicant
  1. Exhibits instructional knowledge of the elements of intercepting and tracking navigational systems and DME arcs by describing
      a. Tuning and identification of a navigational facility
        1) VOR,VOR/DME
          a) Tune VOR receiver to frequeny of appropriate VOR station selected from en route or IAP chart
          b) Identify by Morse code signal and/or voice identification
        2) ADF
          a) Tune ADF receiver to appropriate NDB station with function switch in "Receiver" or "Antenna" postion
          b) Identify by Morse code signal
          c) Move function switch to ADF position
          d) Check needle points to station before and after test function used to swing needle away
          e) Set low but audible volume to continuously monitor station signal
        3) GPS
          a) Check database current
          b) Enter/check proper waypoint
      b. Setting of a selected course on the navigation selector or the correct identification of a selected bearing on the RMI
        1) Copy, readback clearance to confirm correct course radial and track direction (inbound or outbound)
        2) Dial OBS to set course index on correct course
          a) Tracking outbound FROM station, set desired radial under course index
          b) Tracking inbound TO station, set reciprocal of radial under course index
          c) Using RMI, needle head points to station, tail tells radial you are on
      c. Method for determining aircraft position relative to a facility
        1) Center CDI with FROM indication to determine radial
        2) Same technic with VOR/DME yields radial and distance from station
        3) RMI tail tells current radial from station
        4) ADF: RB + MH = MB TO NDB station
      d. Procedure for intercepting and maintaining a selected course
        1) VOR
          a) Course interception
            i) For initial orientaion, turn to fly parallel to and in same direction as desired course
            ii) Determine difference between desired and current radials
            iii) Double the difference to determine intercept angle beween 20 and 90
            iv) Rotate OBS to set desired course at index
            v) Turn to intercept heading
            vi) Fly until CDI centers
            vii) Turn and track desired course inbound or outbound
          b) Course tracking
            i) On intercept, first maintain same heading as desired course
            ii) Note drift off course downwind
            iii) Turn 20° into wind back toward course
            iv) When CDI centers on course, reduce wind correction angle to 10° into wind
            v) Note any drift and adjust wind correction angle appropriately to regain and maintain on course with centered CDI
        2) RMI
          1) Same as VOR
          2) Tail points to current radial
        3) ADF
          a) Course interception
            i) Inbound bearing
            • Turn to parallel desired inbound bearing
            • Note whether station is left or right of nose, double number of degrees of needle deflection to determine interception angle
            • Turn toward desired MB the number of degrees determined for the intercept angle
            • Maintain interception heading until needle is deflected same number of degrees as interception angle minus an appropriate lead
            • Turn and track inbound
            ii) Outbound bearing
            • Same procedure as for inbound except substitute 180° needle position for zero position
          b) Course tracking
            i) Use heading that maintains desired track (constant MB) to or from the station
            ii) To track inbound to station:
            • Turn on course to 0° RB heading
            • Maintain heading until 2°-5° needle deflection (drift angle) is observed
            • Turn in direction of needle deflection to intercept initial MB
            • Intercept angle depends on rate of drift, aircraft speed, station proximity
            • Standard intercept angle = 2 x drift angle
            • Track is intercepted when needle deflection = intercept angle
            • As track is intercepted, turn back in direction of needle until RB = estimated wind correction angle (WCA)
            • If needle deflects off-course, re-intercept track and turn to new RB = new estimated WCA
            iii) To track outbound from station:
            • Same principles as tracking inbound to station
            • Wind correction made toward needle tip deflection
        4) GPS
          a) Intercepting
          b) Tracking
            Keep Actual Track = Desired Track to remain on course
      e. Procedure for intercepting and maintaining a DME arc
        1) VOR/DME
          a) Track inbound (or outbound) on a radial to intercept the DME arc
          b) Lead turn by 0.5 NM with GS < 150 knots
          c) Turn approximately 90
          d) Monitor DME to time rollout to intercept arc
          e) Center the CDI needle upon completion of 90 arc-interception turn, then
          f) Note aircraft heading at left or right side of VOR
          g) Adjust aircraft heading to compensate for wind or to correct for distance
          h) Re-center CDI and note new primary heading indicated whenever the CDI has moved 2-4 from center
        2) GPS
          a) As active GPS WP, select, from database, facility on which DME arc is based
          b) Maintain position on arc by reference to GPS distance
          c) Follow manufacturer/POH recommendations for GPS DME arc approaches (e.g. GNS 530)
      f. Procedure for intercepting a course or localizer from a DME arc
        1) Lead radial is radial at which turn is started to transition from DME arc to inbound course
        2) Lead may be < 5 at < 150 knots
        3) With RMI, note radial to be intercepted and determine approximate lead radial
        4) Intercepting localizer from DME arc is similar
        5) If depicted lead radial provides 7 of lead, then half-standard-rate turn should be used initially
        6) Anticpiate approximately 90° turn
      g. Recognition of navigation facility or waypoint passage
        1) VOR station passage
          a) Approaching station: flickering movements of CDI and TO/FROM indicator
          b) Station passage: first complete reversal of TO/FROM indicator
        2) NDB station passage
          ADF needle points to either wing tip or settles near the 180° postion
      h. Recognition of navigation receiver or facility failure
        1) VOR
          a) Morse code absent
          b) VOR receiver FLAG (signal strenth inadequate) if
            i) VOR facility inop
            ii) VOR too far away
            iii) Airplane too low
          c) Erratic CDI movements
            i) VOR too far away
            ii) Receiver malfunction
        2) ADF
          a) Assume unreliable signal if unable to hear Morse code (or other audible broadcast)
          b) Confirm accuracy of unmoving needle with ADF test function
        3) GPS
          Text message or other signal if GPS position becomes unreliable
  2. Exhibits instructional knowledge of common errors related to intercepting and tracking navigational systems and DME arcs by describing
      a. Incorrect tuning and indentification procedures
        1) Check correct facility
        2) Correct frequency
        3) Correct radio
        4) Correct Morse code/voice ID
      b. Failure to properly set the navigation selector on the course to be intercepted
        Tracking TO or FROM station?
      c. Failure to use proper procedures for course or DME arc interception and tracking
        Follow proper procedures in order like a checklist
      d. Improper procedures for intercepting a course or localizer from a DME arc
        1) Positional awareness
        2) Planning
  3. Demonstrates and simultaneously explains intercepting and tracking navigational systems and DME arcs from an instructional standpoint
  4. Analyzes and corrects simulated common errors related to intercepting and tracking navigational systems and DME arcs

References
14 CFR Part 91
Aviation Instructor's Handbook, FAA-H-8083-9
Instrument Flying Handbook, FAA-H-8083-15, 1999
Instrument Rating PTS, FAA-S-8081-4D, April 2004
AIM


Greg Gordon MD, CFII
Updated: