NOTE.
The existing CPA runway is listed. Pending and future changes at some locations will require a revised runway designation.
14. Simplified Directional Facility (SDF)
14.1 The SDF provides a final approach course similar to that of the ILS localizer. It does not provide glide slope information. A clear understanding of the ILS localizer and the additional factors listed below completely describe the operational characteristics and use of the SDF.
14.2 The SDF transmits signals within the range of
108.10 to 111.95 MHz.
14.3 The approach techniques and procedures used in an SDF instrument approach are essentially the same as those employed in executing a standard no.glide.slope localizer approach except the SDF course may not be aligned with the runway and the course may be wider, resulting in less precision.
14.4 Usable off.course indications are limited to 35 degrees either side of the course centerline. Instrument indications received beyond 35 degrees should be disregarded.
14.5 The SDF antenna may be offset from the runway centerline. Because of this, the angle of convergence between the final approach course and the runway bearing should be determined by reference to the instrument approach procedure chart. This angle is generally not more than 3 degrees. However, it should be noted that inasmuch as the approach course originates at the antenna site, an approach which is continued beyond the runway threshold will lead the aircraft to the SDF offset position rather than along the runway centerline.
14.6 The SDF signal is fixed at either 6 degrees or 12 degrees as necessary to provide maximum “fly ability” and optimum course quality.
14.7
Identification consists of a three.letter identifi-er transmitted in Morse Code on the SDF frequency. The appropriate instrument approach chart will indicate the identifier used at a particular airport.
15.
Microwave Landing System (MLS)
15.1 General
15.1.1 The MLS provides precision navigation guidance for exact alignment and descent of aircraft on approach to a runway. It provides azimuth, elevation, and distance information. The elevation transmitter is located to the side of the runway near the approach threshold. The precision DME, which provides range information, is normally collocated with the azimuth transmitter.
15.1.2 Both lateral and vertical guidance may be displayed on conventional course deviation indica-tors or incorporated into multipurpose cockpit displays. Range information can be displayed by conventional DME indicators and also incorporated into multipurpose displays.
15.1.3 The MLS supplements the ILS as the standard landing system in the U.S. for civil, military, and international civil aviation. At international airports, ILS service is protected to 2010.
15.1.4 The system may be divided into five functions:
15.1.4.1 Approach azimuth.
15.1.4.2 Back azimuth.
15.1.4.3 Approach elevation.
15.1.4.4 Range.
15.1.4.5 Data communications.
15.1.5 The standard configuration of MLS ground equipment includes:
15.1.5.1 An azimuth station to perform functions
15.1.4.1 and 15.1.4.5 above. In addition to providing azimuth navigation guidance, the azimuth station also transmits basic data which consists of information associated directly with the operation of the landing system, as well as advisory data on the performance of the ground equipment.
15.1.5.2 An elevation station to perform function
15.1.4.3.
15.1.5.3 Distance Measuring Equipment (DME) to perform function 15.1.4.4. The DME provides range guidance, both standard (DME/N) and precision DME (DME/P).
15.1.6 MLS Expansion Capabilities. The stan-dard configuration can be expanded by adding one or more of the following functions or characteristics.
15.1.6.1 Back Azimuth. Provides lateral guidance for missed approach and departure navigation.
15.1.6.2 Auxiliary Data Transmissions. Provides additional data, including refined airborne position-ing, meteorological information, runway status, and other supplementary information.
Federal Aviation Administration Twentieth Edition
15.1.6.3 Expanded Service Volume (ESV).
Provides proportional guidance to 60 degrees.
15.1.7 MLS identification is a four.letter designa-tion starting with the letter M. It is transmitted in Morse Code at least six times per minute by the approach azimuth (and back azimuth) ground equipment.
15.2 Approach Azimuth Guidance
15.2.1 The azimuth station transmits MLS angle and data on one of the 200 channels within the frequency range of 5031 to 5091 MHz.
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