AIM

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35

Navigation Aids

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GLS Standard Approach Service Volume

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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.