AIM Text
- General
Approval and use of precision approach systems other than ILS and GLS require the issuance of special instrument approach procedures.
- Special Instrument Approach Procedure
- 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 instrument 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.
- General aviation operators requesting approval 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 authorization through their Operations Specification.
Source: FAA Aeronautical Information Manual · current edition · paragraph 1-1-20.
Research Notes
AIM 1-1-20 covers Ground Based Augmentation System (GBAS) — high-precision GPS augmentation for individual airports.
GBAS concept: Ground reference receivers at an airport measure GPS error and broadcast corrections to aircraft. Higher accuracy than WAAS — enables approach minimums approaching Cat III.
Coverage: Limited to specific airports. Newark, Houston, several others have GBAS installed. Slowly expanding.
Operational scope: Primarily airline use. Aircraft must be GBAS-capable.
Reference: AIM 1-1-20.