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Navigation Aids

FIG 1−1−8

GLS Standard Approach Service Volume

1−1−20. Precision Approach Systems other

than ILS and GLS

a. General

Approval and use of precision approach systems

other than ILS and GLS require the issuance of

special instrument approach procedures.

b. Special Instrument Approach Procedure

1. Special instrument approach procedures

must be issued to the aircraft operator if pilot training,

aircraft equipment, and/or aircraft performance is

different than published procedures. Special instru-

ment approach procedures are not distributed for

general public use. These procedures are issued to an

aircraft operator when the conditions for operations

approval are satisfied.

2. General aviation operators requesting ap-

proval for special procedures should contact the local

Flight Standards District Office to obtain a letter of

authorization. Air carrier operators requesting

approval for use of special procedures should contact

their Certificate Holding District Office for authoriz-

ation through their Operations Specification.

c. Transponder Landing System (TLS)

1. The TLS is designed to provide approach

guidance utilizing existing airborne ILS localizer,

glide slope, and transponder equipment.

2. Ground equipment consists of a transponder

interrogator, sensor arrays to detect lateral and

vertical position, and ILS frequency transmitters. The

TLS detects the aircraft’s position by interrogating its

transponder. It then broadcasts ILS frequency signals

to guide the aircraft along the desired approach path.