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Instrument Procedures Handbook

FAA-H-8083-16B Version 2017
All Library Documents FAA Source

Chapter 4

Approaches

Figure 4-46. Simultaneous Independent Approach Example Using ILS Approaches.
Figure 4-46. Simultaneous Independent Approach Example Using ILS Approaches.
Figure 4-47. Simultaneous independent close parallel approach example using ILS PRM approaches.
Figure 4-47. Simultaneous independent close parallel approach example using ILS PRM approaches.

Localizer Back Course

In cases where an ILS is installed, a back course may be available in conjunction with the localizer. Like the localizer, the back course does not offer a glideslope, but remember that the back course can project a false glideslope signal and the glideslope should be ignored. Reverse sensing occurs on the back course using standard VOR equipment.

With a horizontal situation indicator (HSI) system, reverse sensing is eliminated if it is set appropriately to the front course. [Figure 4-60]

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°.

The LDA is not aligned with the runway. Straight-in minimums may be published where alignment does not exceed 30° between the course and runway. Circling minimums only are published where this alignment exceeds 30°.

Figure 4-48. Example of Simultaneous close parallel instrument approach: Atlanta, Georgia, ILS PRM RWY 10 and AAUP.
Figure 4-48. Example of Simultaneous close parallel instrument approach: Atlanta, Georgia, ILS PRM RWY 10 and AAUP.

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 (Procedure) with Vertical Guidance (aviation) APVs. 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 is required compared to an ILS approach. [Figure 4-61]

Simplified Directional Facility (SDF)

The SDF provides a final approach course similar to that of the ILS localizer. It does not provide glideslope information. A clear understanding of the ILS localizer and the additional factors listed below completely describe the operational characteristics and use of the SDF. [Figure 4-62] The approach techniques and procedures used in an SDF instrument approach are essentially the same as those employed in executing a standard localizer approach except the SDF course may not be aligned with the runway and the course may be wider, resulting in less precision. Like the LOC type approaches, the SDF is an alternative approach that may be installed at an airport for a variety of reasons, including terrain. The final approach is provided a minimum of 250 feet obstacle clearance for straight-in approaches while in the final approach area, which is an area defined for a 6° course: 1,000 feet at or abeam the runway threshold expanding to 19,228 feet (10 NM) from the threshold. The same final approach area for a 12° course is larger. This type of approach is also designed with a maximum descent gradient of 400 feet per NM, unless circling only minimums are authorized.

Figure 4-49. Example of Approach and AAUP used for Simultaneous Offset Instrument Approach Procedure.
Figure 4-49. Example of Approach and AAUP used for Simultaneous Offset Instrument Approach Procedure.
Figure 4-50. Converging approach criteria.
Figure 4-50. Converging approach criteria.
Figure 4-51. Dallas-Fort Worth KDFW, Dallas-Fort Worth, Texas, CONVERGING ILS RWY 35C.
Figure 4-51. Dallas-Fort Worth KDFW, Dallas-Fort Worth, Texas, CONVERGING ILS RWY 35C.
Figure 4-52. Fort Rucker, Alabama, KOZR VOR RWY 6.
Figure 4-52. Fort Rucker, Alabama, KOZR VOR RWY 6.
Figure 4-53. Alexandria International (AEX), Alexandria, Louisiana, KAEX VOR DME RWY 32.
Figure 4-53. Alexandria International (AEX), Alexandria, Louisiana, KAEX VOR DME RWY 32.
Figure 4-54. Carthage/Panola County-Sharpe Field, Carthage, Texas, (K4F2), NDB RWY 35.
Figure 4-54. Carthage/Panola County-Sharpe Field, Carthage, Texas, (K4F2), NDB RWY 35.
Figure 4-55. Tucson/Ryan Field, Tuscson, Arizona, (KRYN), NDB/DME or GPS RWY 6R.
Figure 4-55. Tucson/Ryan Field, Tuscson, Arizona, (KRYN), NDB/DME or GPS RWY 6R.
Figure 4-56. Asheville Regional KAVL, Asheville, North Carolina, radar instrument approach minimums.
Figure 4-56. Asheville Regional KAVL, Asheville, North Carolina, radar instrument approach minimums.