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.

The short answer

AIM 5-4-12 is FAA advisory guidance describing how PAR facilities at some joint-use and military fields monitor aircraft flying a NAVAID instrument approach and issue radar advisories when weather is below VFR minimums (1,000 and 3), at night, or on pilot request. The advisories are a secondary aid only, supporting precision and nonprecision approaches flown under 14 CFR 91.175.

Research Notes

Common Questions

When does a PAR facility provide radar monitoring of my NAVAID approach?

Per AIM 5-4-12, the service is provided when weather is below VFR minimums (1,000 and 3), at night, or when a pilot requests it. It is offered only when the PAR Final Approach Course coincides with the navigational aid’s final approach and only during the PAR’s operational hours.

What advisories will the controller give me during radar monitoring?

The controller advises you of passing the final approach fix inbound (nonprecision) or the outer marker/fix used in lieu of it inbound (precision), plus trend advisories on elevation and azimuth. Glidepath information is given only to aircraft flying a precision approach such as ILS; altitude is not transmitted on nonprecision approaches.

What happens if I drift outside the PAR safety limit?

AIM 5-4-12 states that if, after repeated advisories, the aircraft proceeds outside the PAR safety limit or 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.

5-4-12. Radar Monitoring of Instrument Approaches