7.2.4 Identification is in Morse Code and consists of a three.letter identifier preceded by the letter I ( ) transmitted on the localizer frequency.
EXAMPLE.
I.DIA
7.2.5 The localizer provides course guidance throughout the descent path to the runway threshold from a distance of 18 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:
7.2.5.1 To 10 either side of the course along a radius of 18 NM from the antenna.
7.2.5.2 From 10 to 35either side of the course along a radius of 10 NM. (See FIG ENR 4.1.1.)
7.2.6 Unreliable signals may be received outside these areas.
FIG ENR 4.1.1
Limits of Localizer Coverage
7.3 Localizer.Type Directional Aid
7.3.1 The localizer.type directional aid (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) instal-lation, which may have a course width of 6 degrees or 12 degrees.
7.3.2 The LDA is not aligned with the runway. Straight.in minimums may be published where alignment does not exceed 30 degrees between the course and runway. Circling minimums only are published where this alignment exceeds 30 degrees.
7.3.3 A very limited number of LDA approaches also incorporate a glideslope. These are annotated in the plan view of the instrument approach chart with a note, “LDA/Glideslope.” These procedures fall under a newly defined category of approaches called Approach with Vertical Guidance (APV) described in Section , paragraph 12., Instrument Approach Procedure Charts, subparagraph 12.1.7.2, Approach with Vertical Guidance (APV). LDA minima for with and without glideslope 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.
7.4 Glide Slope/Glide Path
7.4.1 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.
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 a glide slope is specified on the approach and landing chart.
7.4.2 The glide slope transmitter is located between 750 and 1,250 feet from the approach end of the runway (down the runway) and offset 250.600 feet from the runway centerline. It transmits a glide path beam 1.4 degrees wide (vertically).
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