Radar Monitoring of Instrument Approaches — AIM 5-4-12

AIM Text

PAR facilities operated by the FAA and the military services at some joint-use (civil and military) and military installations monitor aircraft on instrument approaches and issue radar advisories to the pilot when weather is below VFR minimums (1,000 and 3), at night, or when requested by a pilot. This service is provided only when the PAR Final Approach Course coincides with the final approach of the navigational aid and only during the operational hours of the PAR. The radar advisories serve only as a secondary aid since the pilot has selected the navigational aid as the primary aid for the approach.
Prior to starting final approach, the pilot will be advised of the frequency on which the advisories will be transmitted. If, for any reason, radar advisories cannot be furnished, the pilot will be so advised.
Advisory information, derived from radar observations, includes information on:
1. Passing the final approach fix inbound (nonprecision approach) or passing the outer marker or fix used in lieu of the outer marker inbound (precision approach).
  
  NOTE-
  
  At this point, the pilot may be requested to report sighting the approach lights or the runway.
2. Trend advisories with respect to elevation and/or azimuth radar position and movement will be provided.
  
  NOTE-
  
  Whenever the aircraft nears the PAR safety limit, the pilot will be advised that the aircraft is well above or below the glidepath or well left or right of course. Glidepath information is given only to those aircraft executing a precision approach, such as ILS. Altitude information is not transmitted to aircraft executing other than precision approaches because the descent portions of these approaches generally do not coincide with the depicted PAR glidepath.
3. If, after repeated advisories, the aircraft proceeds outside the PAR safety limit or if a radical deviation is observed, the pilot will be advised to execute a missed approach unless the prescribed visual reference with the surface is established.
Radar service is automatically terminated upon completion of the approach.

Source: FAA Aeronautical Information Manual · current edition · paragraph 5-4-12.

Research Notes

AIM 5-4-12 covers VOR Approach — the conventional non-precision instrument approach using a VOR (Very High Frequency Omnidirectional Range) station.

VOR approach characteristics:

Lateral guidance only (no vertical)
MDA (Minimum Descent Altitude) is the floor — descend no lower until visual
FAF (Final Approach Fix) is typically a DME distance from the VOR, or a separate fix
Approach typically requires VOR receiver + DME or RNAV for FAF identification

Variants:

VOR-A, VOR-B, etc.: circling approaches (not aligned with runway)
VOR/DME: requires DME for FAF or step-down fix
VOR-RWY XX: aligned with a specific runway for straight-in landing

Status: Many VOR approaches have been retired and replaced with RNAV (GPS) approaches. Some VOR approaches remain at smaller airports or as backup options.

Reference: AIM 5-4-12; FAA-H-8083-16 Chapter 5; AIM 1-1-3 (VOR).

5-4-12. Radar Monitoring of Instrument Approaches

AIM Text

Research Notes

This free course covers everything you need to get started the right way.