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Teaching and Learning Flying - Airplane Instrument Rating

ILS Approach (LOC Approach, BC Approach)


DEFINITION

ILS approach - a precision instrument approach with final approach course lateral guidance provided by the localizer (LOC) and descent path guidance provided by the glideslope (GS) of a full Instrument Landing System
LOC approach - a nonprecision instrument approach with final approach course guidance provided by a localizer (LOC)
BC approach- a nonprecision instrument approach with final approach course guidance provided by a localizer back-course (BC)

SAFETY FACTORS

Knowledge and skill in ILS approaches may be used to safely let down in low IMC to many airports.
Safe ILS approach depends on
    Proper functioning, tuning, identification and monitoring of the ILS
    Understanding of ILS equipment and use
    Good communication with ATC
    Proficient AIF while performing precise ILS navigation

TOLERANCES

Instrument Rating PTS (FAA-S-8081-4D) VI.B. Precision approach (PA)
To determine that the applicant:
  1. Exhibits adequate knowledge of the precision instrument approach procedures.
  2. Accomplishes the appropriate precision instrument approaches as selected by the examiner.
  3. Establishes two-way communications with ATC using the proper communications phraseology and techniques, as required for the phase of flight or approach segment.
  4. Complies, in a timely manner, with all clearances, instructions, and procedures.
  5. Advises ATC anytime that the applicant is unable to comply with a clearance.
  6. Establishes the appropriate airplane configuration and airspeed/V-speed considering turbulence, wind shear, microburst conditions, or other meteorologic and operating conditions.
  7. Completes the aircraft checklist items appropriate to the phase of flight or approach segment, including engine out approach and landing checklists, if appropriate.
  8. Prior to beginning the final approach segment, maintains the desired altitude +/-100 feet, the desired airspeed within +/-10 knots, the desired heading within +/-10 °; and accurately tracks radials, courses, and bearings.
  9. Selects, tunes, identifies, and monitors the operational status of ground and airplane navigation equipment used for the approach.
  10. Applies the necessary adjustments to the published DA/DH and visibility criteria for the airplane approach category as required, such as -
      a. NOTAMs
      b. inoperative airplane and ground navigation equipment
      c. inoperative visual aids associated with the landing environment
      d. NWS reporting factors and critera
  11. Establishes a predetermined rate of descent at the point where the electronic glide slope begins, which approximates that required for the aircraft to follow the glide slope.
  12. Maintains a stabilized final approach, from the Final Approach Fix to DA/DH allowing no more than ¾ scale deflection of either glide slope or localizer indications and maintains the desired airspeed within +/-10 knots.
  13. A missed approach or transition to a landing shall be initiated at Decision Height.
  14. Initiates immediately the missed approach when at the DA/DH, and the required visual references for the runway are not unmistakably visible and identifiable.
  15. Transitions to a normal landing approach (missed approach for seaplanes) only when the aircraft is in a position from which a descent to a landing on the runway can be made at a normal rate of descent using normal maneuvering.
  16. Maintains localizer and glide slope within ¾ scale deflection of the indicators during the visual descent from DA/DH to a point over the runway where glide slope must be abandoned to accomplish a normal landing.
VI. C. Missed approach
To determine that the applicant:
  1. Exhibits adequate knowledge of the elements related to missed approach procedures associated with standard instrument approaches.
  2. Initiates the missed approach promptly by applying power, establishing a climb attitude, and reducing drag in accordance with the aircraft manufacturer's recommendations.
  3. Reports to ATC beginning the missed approach procedure.
  4. Complies with the published or alternate missed approach procedure.
  5. Advises ATC or examiner anytime that the aircraft is unable to comply with a clearance, restriction, or climb gradient.
  6. Follows the recommended checklist items appropriate to the go-around procedure.
  7. Requests, if appropriate, ATC clearance to the alternate airport, clearance limit, or as directed by the examiner.
  8. Maintains the recommended airspeed within +/-10 knots; heading, course, or bearing within +/-10°; and altitude(s) within +/-100 feet during the missed approach procedure.

OBJECTIVES

Encourage mastery of the ILS approach
Develop student knowledge and skill in flying ILS approches to meet the Instrument Pilot PTS

PROCEDURES

Preflight
Discussion Inflight
  • Demonstrate
  • Coach student practice
      ILS
      LOC
      BC
  • Maintenance of altitude, airspeed and track, where applicable
      1) Beginning prior to glide slope intercept, maintain
        a) Altitude +/- 100 feet (aim for +/- 20 feet)
        b) Heading +/- 10° with stable wind drift correction (aim for +/- 2°)
        c) Airspeed +/- 10 knots (aim for +/- 2 knots)
        d) CDI less that ¾-scale deflection (aim for < 1 dot)
      2) On descent on glidepath, allow no more than ¾-scale deflection of either glide slope or localizer indicator (aim for < 1 dot) until over the runway
      3) C-TR182: maintain approach airspeed, 100 KIAS, during missed approach climb
  • Establishment and maintenance of an appropriate rate of descent during the final approach segment
      1) Maintain a stabilized final approach from the final approach fix to the DA/DH, allow no more that ¾-scale deflection of either glide slope or localizer indications (aim for < 1 dot), and maintain the desired airspeed within +/-10 knots (aim for +/-2 knots)
      2) Use small heading changes (<2°) to track LOC
      3) If airplane is properly trimmed for approach speed, both glide slope and airspeed can be maintained with small power adjustments
      4) If small power adjustments not enough then
        i) Adjust pitch to maintain desired rate of descent, and
        ii) Adjust power to maintain airspeed
Postflight
  • Critique student performance

COMMON ERRORS

  • Failure to have essential knowledge of the information on the instrument approach chart
      1) Plan ahead
      2) Know approach(es) to expect (ATC, ATIS)
      3) Study, record, memorize key data in advance
        How low? How long? How far? Which way?
      4) Use PC or simulator to practice flying approaches to destinations of upcoming flights
  • Incorrect communications procedures or noncompliance with ATC clearances or instructions
      If cannot comply, request amendment
  • Failure to accomplish checklist items
      1) Start before landing checklist on initial approach segment or on initial vectors for approach
      2) Complete before landing checklist at glide slope intercept (gear down)
  • Faulty basic instrument flying technic
      May be due to cockpit disorganization and increased workload
  • Inappropriate application of DA/DH
      1) May indicate inadequate speed of cross-check and interpretation during high workload time
      2) Stay on localizer and glide slope until over the runway

References
Greg Gordon MD, CFII
Updated: