Ibload486

This section prescribes the performance requirements for localizer equipment components of the ISMLS.

Definition of localizer in the Definitions.net dictionary. Meaning of localizer. What does localizer mean? Information and translations of localizer in the most comprehensive dictionary definitions resource on the web. Definition of localizer in the Definitions.net dictionary. Meaning of localizer. What does localizer mean? Information and translations of localizer in the most comprehensive dictionary definitions resource on. The LOCalizer tag can be placed in the breast up to 30 days before surgery – this takes place under local anesthesia (the area is numbed) and the tag is inserted with a needle under ultrasound or x-ray guidance. Each tag has a unique identification number to clearly mark the lesion.

(a) The localizer antenna system must:

(1) Be located on the extension of the centerline of the runway at the stop end;

(2) Be adjusted so that the course line be on a vertical plane containing the centerline of the runway served;

(3) Have the minimum height necessary to comply with the coverage requirements prescribed in paragraph (j) of this section;

(4) Be located at a distance from the stop end of the runway that is consistent with safe obstruction clearance practices;

(5) Not obscure any light of the approach landing system; and

(6) Be installed on frangible mounts or beyond the 1000′ light bar.

(b) On runways where limited terrain prevents the localizer antennae from being positioned on the runway centerline extended, and the cost of the land fill or a tall tower antenna support is prohibitive, the localizer antenna array may be offset, including a collocated ground station, so that the course intercepts the centerline at a point determined by the amount of the angular offset and the glide path angle. If other than a runway centerline localizer is used, the criteria in subpart C of part 97 of this chapter is applicable.

(c) At locations where two separate ISMLS facilities serve opposite ends of of a single runway, an interlock must ensure that only the facility serving the approach direction being used will radiate.

(d) The radiation from the localizer antenna system must produce a composite field pattern which is pulse duration modulated, the time average equivalent to amplitude modulation by a 90 Hz and 150 Hz tone. The localizer station must transmit angular guidance information over a C-band microwave carrier on narrow, scanned antenna beams that are encoded to produce a modulation in space which, after averaging over several beam scans, is equivalent to the modulation used for conventional ILS as specified in subpart C of this part. The radiation field pattern must produce a course sector with one tone predominating on one side of the course and with the other tone predominating on the opposite side. When an observer faces the localizer from the approach end of the runway, the depth of modulation of the radio frequency carrier due to the 150 Hz tone must predominate on his right hand and that due to the 90 Hz tone must predominate on his left hand.

(e) All horizontal angles employed in specifying the localizer field patterns must originate from the center of the localizer antenna system which provides the signals used in the front course sector.

(f) The ISMLS course sector angle must be adjustable between 3 degrees and 9 degrees. The applicable course sector angle will be established and approved on an individual basis.

(g) The ISMLS localizer must operate in the band 5000 MHz to 5030 MHz. The frequency tolerance may not exceed ±0.0001 percent.

(h) The emission from the localizer must be vertically polarized. The horizontally polarized component of the radiation of the course line may not exceed that which corresponds to a DDM error of 0.016 when an aircraft is positioned on the course line and is in a roll attitude of 20 degrees from the horizontal.

(i) The localizer must provide signals sufficient to allow satisfactory operation of a typical aircraft installation within the localizer and glide path coverage sectors. The localizer coverage sector must extend from the center of the localizer antenna system to distances of 18 nautical miles minimum within ±10 degrees from the front course line, and 10 nautical miles minimum between ±10 degrees and ±35 degrees from the front course line. The ISMLS localizer signals must be receivable at the distances specified up from a surface extending outward from the localizer antenna and within a sector in the elevation plane from 0.300 to 1.750 of the established glide path angle (θ).

(j) Except as provided in paragraph (k) of this section, in all parts of the coverage volume specified in paragraph (i) of this section, the peak field strength may not be less than −87 dBW/m 2, and must permit satisfactory operational usage of ISMLS localizer facilities.

(k) The minimum peak field strength on the ISMLS glide path and within the localizer course sector from a distance of 10 nautical miles to a height of 100 feet (30 meters) above the horizontal plane containing the threshold, may not be less than + 87 dBW/m 2.

(l) Above 16 degrees, the ISMLS localizer signals must be reduced to as low a value as practicable.

(m) Bends in the course line may not have amplitudes which exceed the following:

Zone	Amplitude (DDM) (95 pct. probability)
Outer limit of coverage to:
ISMLS point “A”	0.031.
ISMLS point “A” to ISMLS point “B”	0.031 at ISMLS point “A” decreasing at linear rate to 0.015 at ISMLS point “B”.
ISMLS point “B” to ISMLS point “C”	0.015.

(n) The amplitudes referred to in paragraph (m) of this section are the DDMs due to bends as realized on the mean course line, when correctly adjusted.

(o) The radio frequency carrier must meet the following requirements:

(1) The nominal depth of modulation of the radio frequency carrier due to each of the 90 Hz and 150 Hz tones must be 20 percent along the course line.

(2) The depth of modulation of the radio frequency carrier due to each of the 90 Hz and 150 Hz tones must be between 18 and 22 percent.

(3) The frequency tolerance of the 90 Hz and 150 Hz modulated tones must be within ±25 percent.

(4) Total harmonic content of the 90 Hz tone may not exceed 10 percent.

(5) Total harmonic content of the 150 Hz tone may not exceed 10 percent. However, a 300 Hz tone may be transmitted for identification purposes.

(6) At every half cycle of the combined 90 Hz and 150 Hz wave form, the modulation tones must be phase-locked so that within the half course sector, the demodulated 90 Hz and 150 Hz wave forms pass through zero in the same direction within 20 degrees with phase relative to the 150 Hz component. However, the phase need not be measured within the half course sector.

(p) The mean course line must be adjusted and maintained within ±.015DDM from the runway centerline at the ISMLS reference datum.

(q) The nominal displacement sensitivity within the half course sector at the ISMLS reference datum, must be 0.00145 DDM/meter (0.00044DDM/foot). However, where the specified nominal displacement sensitivity cannot be met, the displacement sensitivity must be adjusted as near as possible to that value.

(r) The lateral displacement sensitivity must be adjusted and maintained within 17 percent of the nominal value. Nominal sector width at the ISMLS reference datum is 210 meters (700 feet).

(s) The increase of DDM must be substantially linear with respect to angular displacement from the front course line where DDM is zero, up to angle on either side of the front course line where the DDM is 0.180. From that angle to ±10 degrees, the DDM may not be less than 0.180. From ±10 degrees to ±35 degrees, the DDM may not be less than 0.155.

(t) The localizer must provide for the simultaneous transmission of an identification signal which meets the following:

(1) It must be specific to the runway and approach direction, on the same radio frequency carrier, as used for the localizer function.

(2) Transmission of the identification signal may not interfere in any way with the basic localizer function.

(3) The signal must be produced by pulse duration modulation of the radio frequency carrier resulting in a detected audio tone in the airborne VHF receiver of 1020 Hz ±50Hz.

(4) The depth of modulation must be between the limits of 10 and 12 percent.

(5) The emissions carrying the identification signal must be vertically polarized.

(6) The identification signal must employ the International Morse Code and consist of three letters. It must be preceded by the International Morse Code signal of the letter “M” followed by a short pause where it is necessary to distinguish the ISMLS facility from other navigational facilities in the immediate area. At airports where both an ISMLS and an ILS are in operation, each facility must have a different identification call sign.

(7) The signal must be transmitted at a speed corresponding to approximately seven words per minute, and must be repeated at approximately equal intervals, not less than six times per minute, during which time the localizer is available for operational use. When the localizer is not available for transmission, the identification signal must be suppressed.

• Home»
• notebook»
• avionics and instruments»
• instrument landing system

Introduction:

• The Instrument Landing System provides an approach path for the exact alignment and descent of an aircraft on the final approach to a runway
• The pilot receives guidance information through a ground-based directional transmitter:
  • The localizer, providing horizontal guidance, and;
  • The glide-slope, providing vertical guidance
• Landing information is then supplemented with range information through:
  • Marker Beacons;
  • Compass Locators, or;
  • Distance Measuring Equipment, which is simplified via frequency pairing
• Finally, to aid the transition, visual information is provided through the use of airport lighting
• Other approaches use the same equipment but are similar to localizers, such as Localizer Type Directional Aid Approaches and Simplified Directional Facility Approaches
• These approaches all come with their unique set of minimums to provide a margin for error and safety buffer to compensate for potential limitations and malfunctions
• The system is not foolproof, however, and so pilots must be aware of the factors which can cause course distortion to ensure they are receiving reliable signals
• With a background in system function, pilots then perform an instrument landing procedure as published or via radar vectors

Guidance Information:

• Guidance is provided through a ground based system that consists of several components [Figure 1]

• Localizer:

  • The localizer (LOC) provides lateral course guidance during an approach to landing
  • Instrumentation operates between 108 - 111.95 MHz on one of 40 channels that transmits from a ground node
    • The localizer's approach course, used with other functional parts (glide-slope, marker beacons, etc.), is called the front course
      • Some localizers may transmit the course line along the extended centerline of a runway, in the opposite direction to the front course, which is called the back course
      • CAUTION:
        Unless the aircraft's Instrument Landing System (ILS) equipment includes reverse sensing capability, when flying inbound on the back course, it is necessary to steer the aircraft in the direction opposite the needle deflection when making corrections off-course to on-course. This 'flying away from the needle' is also required when flying outbound on the localizer's front course. Do not use back course signals for approach unless there is a published back course approach procedure for that particular runway and Air Traffic Control (ATC) authorizes the approach
  • The localizer signal transmits at the far end of the runway
  • Adjusted for a course width of (full-scale fly-left to a full scale fly-right) of 700' at the runway threshold
    • The localizer provides course guidance throughout the descent path to the runway threshold from a distance of 18 Nautical Miles (NM) from the antenna between an altitude of 1,000 feet above the highest terrain along the course line and 4,500 feet above the elevation of the antenna site
    • Proper off-course indications are provided throughout the following angular areas of the operational service volume: [Figure 2]
      • To 10° on either side of the course along a radius of 18 NM from the antenna; and
      • From 10 to 35° on either side of the course along a radius of 10 NM
    • Signals may be received outside of the advertised vertical and lateral limits but are considered unreliable
      • The areas described in and depicted in [Figure 3] represent a Standard Service Volume (SSV) localizer. All charted procedures with localizer coverage beyond the 18 NM SSV have been through the approval process for Expanded Service Volume (ESV) and validated by flight inspection
  • Identification is in International Morse Code and consists of a three-letter identifier preceded by the letter I (- -) transmitted on the localizer frequency
    • Three letter id preceded by I (I-DAB)
    • The approach plate displays the Morse code pattern

• glide-slope/Glide Path:

  • The UHF glide-slope transmitter, operating on one of the 40 ILS channels within the frequency range 329.15 MHz, to 335.00 MHz radiates its signals in the direction of the localizer front course
  • The term glide path means that portion of the glide-slope that intersects the localizer
    • CAUTION: False glide-slope signals may exist in the area of the localizer back course approach, which can cause the glide-slope flag alarm to disappear and present unreliable glide-slope information. Disregard all glide-slope signal indications when making a localizer back course approach unless the approach and landing charts specify a glide-slope
  • The transmitter is located 750 - 1,250' from the approach end offset 250 - 650' from centerline
  • It transmits a glide-path beam 1.4° wide (vertically)
  • The signal is considered accurate down to the lowest decision height (DH) published on an ILS approach procedure
    • Any reference to glide-path indications below that height is supplemented by visual reference to the runway environment
    • Glide-paths with no published DH are usable to runway threshold
  • The glide-slope is normally usable to a distance of 10 NM
  • However, at some locations, the glide-slope has been certified for an extended service volume that exceeds 10 NM
  • Be alert for false glide-slopes and reverse sensing when intercepting the glide-slope
    • False courses and reverse sensing can occur when intercepting the ILS at angles considerably greater than the published path
    • It is therefore extremely important to maintain glide-slope to assure obstacle/terrain clearance is maintained
  • The published glide-slope threshold crossing height (TCH) DOES NOT represent the height of the actual glide path on-course indication above the runway threshold
    • It is a reference for planning purposes which represents the height above the runway threshold that an aircraft's glide-slope antenna should be if that aircraft remains on a trajectory formed by the four-mile-to-middle marker glide-path segment
    • TCH does not coincide with GS altitude over threshold, but rather with the antennas should be (think bigger aircraft)
  • Pilots must be aware of the vertical height between the aircraft's glide-slope antenna and the main gear in the landing configuration and, at the DH, plan to adjust the descent angle accordingly if the published TCH indicates the wheel crossing height over the runway threshold may not be satisfactory
    • Tests indicate a comfortable wheel crossing height is approximately 20 to 30', depending on the type of aircraft
  • TCH for a runway is established based on several factors, including the largest aircraft category that normally uses the runway, how airport layout affects the glide-slope antenna placement, and terrain. A higher than optimum TCH, with the same glide path angle, may cause the aircraft to touch down further from the threshold if the approache's trajectory is maintained until the flare. Pilots should consider the effect of a high TCH on the runway available for stopping the aircraft

Range Information:

• Distance Measuring Equipment:

  • When installed with the ILS and specified in the approach procedure, Distance Measuring Equipment (DME) may be used:
    • In lieu of the Outer Marker (OM);
    • As a back course (BC) Final Approach Fix (FAF); and
    • To establish other fixes on the localizer course
  • In some cases, DME from a separate facility may be used within Terminal Instrument Procedures (TERPS) limitations:
    • To provide an arc for the initial approach segment;
    • FAF for BC approaches; and
    • Substitute for OM

• Marker Beacons:

  • ILS marker beacons have a rated power output of 3 watts or less and an antenna array designed to produce an elliptical pattern with dimensions, at 1,000 feet above the antenna, of approximately 2,400 feet in width and 4,200 feet in length
  • Airborne marker beacon receivers with a selective sensitivity feature should always be operated in the 'low' sensitivity position for proper reception of ILS marker beacons
  • ILS systems may have an associated OM. A Middle Marker (MM) is no longer required. Locations with a Category II ILS also have an Inner Marker (IM)
    • Due to advances in both ground navigation equipment and airborne avionics, as well as the numerous means that may substitute a marker beacon, the current requirements for the use of marker beacons are:
      • An OM or suitable substitute identifies the FAF for non-precision approach (NPA) operations (for example, localizer only); and
      • The MM indicates a position approximately 3,500 feet from the landing threshold. This is also the position where an aircraft on the glide path will be at an altitude of approximately 200 feet above the touchdown zone's elevation. An MM is no longer operationally required. There are some MMs still in use, but no MMs are being installed at new ILS sites by the FAA; and
      • An IM, where installed, indicates the point at which an aircraft is at decision height on the glide path during a Category II ILS approach. An Initial Marker (IM) is only required for CAT II operations that do not have a published radio altitude (RA) minimum
  • A back course marker normally indicates the ILS back course final approach fix where approach descent is commenced
  • The following means may be used to substitute for the OM:
    • Compass locator; or
    • Precision Approach Radar (PAR); or
    • Airport Surveillance Radar (ASR); or
    • DME, Very-High Frequency Omni-directional Range (VOR) radial intersections or Nondirectional Beacon (NDB) fixes authorized in the Standard Instrument Approach Procedure; or
    • A suitable RNAV system with a Global Positioning System (GPS), capable of fix identification on a Standard Instrument Approach Procedure

• Compass Locator:

  • Similar to an NDB, a compass locator is a low to medium powered beacon, which is the precursor to modern-day marker beacons
  • Compass locators provide the same basic information to the pilot as a marker beacon
  • Compass locator transmitters are often situated at the MM and OM sites
  • The transmitters have a power of less than 25 watts, a range of at least 15 miles, and operate between 190 and 535 kHz
  • At some locations, higher-powered radio beacons, up to 400 watts, are used as OM compass locators
  • Compass locators transmit two-letter identification groups [Figure 4]
  • The outer locator transmits the first two letters of the localizer identification group, and the middle locator transmits the last two letters of the localizer identification group
  • Provide a transition from en-route to approach phase
  • The transmitters have a power of less than 25 watts, a range of at least 15 miles, and operate between 190 and 535 kHz
  • At some locations, higher-powered radio beacons, up to 400 watts, are used as OM compass locators
  • OM: First 2 letters of loc id group
  • MM: Last 2 letters of loc id group

ILS Frequency Pairs:

• The ILS pairs frequencies to give localizer and glide-slope information on a single frequency
  • As far as the pilot is concerned, you only need to input the Very-High Frequency (VHF) frequency, as the Ultra-High Frequency (UHF) is automatically tied to that
  • This single ILS frequency is found in the top left of the approach plate
  • The list of paired frequencies is in the Aeronautical Information Manual under paragraph 1-1-9, Instrument Landing System

Localizer Type Directional Aid (LDA):

• The LDA is of comparable use and accuracy to a localizer but is not part of a complete ILS
• The LDA course usually provides a more precise approach course than the similar Simplified Directional Facility (SDF) installation, which may have a course width of 6 or 12°
• LDAs are not aligned with the runway
• If less than 30° off, straight in minimums are published
• If more than 30° off, circle to land minimums are published
• Some approaches have glide-slopes referred to Approaches with Vertical Guidance (APVs)
  • APVs are annotated in the plan view of the instrument approach chart with a note, 'LDA/Glide-slope'
  • These procedures fall under a newly defined category of approaches called Approaches with Vertical Guidance (APV)
  • LDA minima for with and without glide-slope (GS) is provided and annotated on the minima lines of the approach chart as S-LDA/GS and S-LDA
  • Because the final approach course is not aligned with the runway centerline, additional maneuvering will be required compared to an ILS approach
  • Note that approaches with vertical guidance are just that, guidance
    • These approaches are non-precision approaches, not precision

Simplified Directional Facility:

• The SDF provides a final approach course similar to that of the ILS localizer but no glide-slope information
• Operates on the same localizer frequency (108.10 to 111.95)
• Techniques and procedures used in an SDF instrument approach are the same as those in a localizer, except the final approach course may not be aligned with the runway, and the course may be wider, resulting in less precision
  • Note that as the approach course originates at the antenna site, an approach that flown beyond the runway threshold will lead the aircraft to the SDF offset position rather than along the runway centerline
• Usable to 35° on either side of course line, same as a localizer
  • Any signals received outside of this range shall be considered unusable for navigation
• The antenna may be offset from the runway centerline, and so the final approach course and the runway bearing should be referenced on the IAP chart
  • Normally not more than 3°; however, if the approach continues beyond the runway threshold, you will be in a bad position to land
• The signal is fixed at either 6 or 12° as necessary to provide maximum fly-ability and optimum course quality
• Identification is provided through a 3-letter Morse code indicated on the instrument approach chart for a particular airport

ILS Minimums:

• The lowest authorized ILS minimums, with all required ground and airborne systems components operative, are:

• Category (CAT) I:

  • Decision Height (DH): 200'
  • Runway Visual Range (RVR): 2,400' (1,800 w/ Touch Down Zone (TDZ) and centerline lighting) or (with Autopilot or Flight Director (FD) or Heads Up Display (HUD), RVR 1,800')

• Special Authorization Category I:

  • DH: 150'
  • RVR: 1,400'
  • HUD to DH

• Category (CAT) II:

  • DH: 100'
  • RVR: 1,200' with auto-land or HUD to touchdown and noted on authorization, RVR 1,000'

• Special Authorization Category II with Reduced Lighting:

  • DH: 100
  • RVR: 1,200 with auto land or HUD to touchdown and noted on authorization
    • Touchdown zone, centerline lighting, and ALSF-2 are not required);

• Category (CAT) IIIa:

  • No DH or DH below 100'
  • RVR not less than 700'

• Category (CAT) IIIb:

  • No DH or DH below 50'
  • RVR Less than 700' but not less than 150'

• Category (CAT) IIIc:

  • No DH
  • No RVR minimum
• Note that special authorization and equipment required for Categories II and III

ILS Limitations & Malfunctions:

• Inoperative ILS Components:

  • Inoperative localizer:

    ILS not authorized

  • Inoperative glide-slope:

    ILS reverts to a non-precision, localizer approach if you have a failure of the GS after the FAF inform the controller you are switching to a localizer approach while climbing or descending to the Minimum Descent Altitude (MDA) (no longer a DH)
  • See the inoperative component table in the U.S. Government Terminal Procedures Publication (TPP) for adjustments to minimums due to inoperative airborne or ground system equipment

• ILS Course Distortion:

  • All pilots should be aware that signal interferences may occur when surface vehicles, aircraft, or both operated near the localizer or glide-slope antennas
  • At controlled airports, ATC issues control instructions to avoid interfering operations within ILS critical areas during the hours the Airport Traffic Control Tower (ATCT)

  • ILS Critical Areas:

    • Ground control will advise you when to hold short of critical areas
    • Issued when official weather observation is a ceiling of less than 800 feet and/or visibility 2 miles
    • Requires the pilot to keep the entire aircraft clear of the associated marking and remain on the safe side of the ILS Critical Area

• Localizer Critical Area:

  • Except for aircraft that land, exit a runway, depart, or execute a missed approach, vehicles and aircraft are not authorized in or over the critical area when an arriving aircraft is inside the OM or the fix used in lieu of the OM
  • Additionally, when conditions are less than the reported ceiling 200 feet or RVR less than 2,000 feet, do not authorize vehicles or aircraft operations in or over the area when an arriving aircraft is inside the MM, or in the absence of a MM, 1/2 mile final

• Glide-slope Critical Area:

  • Do not authorize vehicles or aircraft operations in or over the area when an arriving aircraft is inside the ILS outer marker (OM), or the fix used in lieu of the OM, unless the arriving aircraft has reported the runway in sight and is circling or side-stepping to land on another runway
  • When official weather observation is at or above ceiling 800 feet and/or visibility 2 miles:
    • No critical area protective action is provided under these conditions
    • A flight crew desiring autoland or coupled approaches must advise ATC under these conditions to ensure that the ILS critical areas are protected when the aircraft is inside the ILS MM
      • Pilot: 'Denver Tower, United 1153, Request [Autoland/Coupled] Approach [Runway]'
      • ATC: 'United 1153, Denver Tower, Roger, Critical Areas not protected'
    • Safety works best when we help each other, so if the weather is at or below 800' or 2 miles and ATC hasn't issued you an ILS hold, it doesn't hurt to hold short and ask anyway
      • Remember, ILS Critical Areas are only mandatory when ATC issues a hold. If the field is uncontrolled, there is no requirement to hold short of the ILS Critical Area
      • That said, be mindful of the weather and inbound aircraft, and consider holding short if conditions warrant
    • Aircraft holding below 5,000' between the outer marker and the airport may cause localizer signal variations for aircraft conducting the ILS approach
      • Accordingly, such holding is not authorized when weather or visibility conditions are less than ceiling 800' and/or visibility 2 miles
    • Vehicular traffic not subject to ATC may cause momentary deviation to ILS course or glide-slope signals
      • Also, critical areas are not protected at uncontrolled airports or airports with an operating control tower when weather or visibility conditions are above those requiring protective measures
      • Aircraft conducting coupled or autoland operations should be especially alert in monitoring automatic flight control systems
    • Note that unless otherwise coordinated through Flight Standards, ILS signals to Category I runways are not flight inspected below the point that is 100 feet less than the decision altitude (DA). Guidance signal anomalies may be encountered below this altitude

Instrument Landing System Procedure:

• Request the ILS approach from ATC
• Follow the assigned clearance or radar vectors, as assigned by ATC
• Complete any appropriate checklists, ensuring the aircraft is in the landing configuration before intercepting the glide-slope
• Upon intercepting the glide-slope (FAF), reduce power, and adjust pitch to maintain glide-slope
  • The glideslope angle is on the instrument approach chart, generally around 3°
• Make small adjustments as required
  • Corrections will become more sensitive as you get closer to the airport, so it is imperative to stabilize your approach as early as possible
  • To recapture the glideslope, corrections should be within a degree or two of pitch, or a couple of hundred feet per minute on the rate of descent
  • To recapture the localizer, stay inside of the heading bug, if available, or 5 degrees left or right of center if none is
• At the OM or Locator Outer Marker (LOM):
  • Check the altimeter crossing the OM/LOM
  • Perform the 5Ts:
    • Time: Note the time
    • Turn: to track the inbound course
    • Twist: Verify the Omni Bearing Selector (OBS) is set to inbound course:
    • Throttle: Maintain approach speed
    • Talk: Make required reports
• At 1000' above DA(H), call out '1000 above DA(H)'
• At 500' above DA(H), call out '500 above DA(H),' and complete a 'GUMP' (Gas, Undercarriage, Mixture, Propeller) check
• At 100' above DA(H), call out '100 above DA(H)'
• Upon reaching DA(H):
  • Continue the approach if the runway environment is in sight, or;
    • Descend no lower than 100 above touchdown zone elevation when referencing the approach light system without seeing the red terminating bars or red side-row bars
  • Call out 'missed approach,' and execute the published missed approach procedure if ATC does not direct a different procedure
• With the runway in sight and when in a position from which a descent to a landing on the indented runway can be made at a normal rate of descent using normal maneuvers
  • Callout, 'Runway in Sight, Landing'
  • Maintain the localizer and glideslope during the visual descent to a point over the runway where the a normal landing can be performed
• At or below V_FE, set the flaps as appropriate for landing

Radar Vectors:

• On dogleg to final when within 5-7 NM of the FAF execute the above procedures accomplish the same procedures as above starting with step 6
• If above the localizer minimums and you lose glide-slope then you may request the localizer if you lost a localizer approach, however, if you lose glide-slope below localizer minimums, go mist and if you lose the localizer in any situation, go missed

Conclusion:

Localizer Vs Ils

• Some final approach fixes may be designated with cross radials using VORs, however, de-selecting the ILS is NOT an acceptable method of identifying the FAF
• Where a complete ILS system is installed on each end of a runway; (i.e., the approach end of Runway 4 and the approach end of Runway 22), the ILS systems are not in service simultaneously
• Pilots should be aware of the possibility of momentary erroneous indications on cockpit displays when the primary signal generator for a ground-based navigational transmitter is inoperative
  • Pilots should disregard any navigation indication, regardless of its apparent validity, if designated inoperative by Notice to Airmen
• See also:
• Still looking for something? Continue searching:

Localizer Approach

Difference Between Ils And Localizer

References: