AIM ¶ 5-4-12 — Radar Monitoring Instrument Approaches
AIM 5-4-12 explains PAR radar monitoring of instrument approaches, advisory triggers, glidepath info, and safety limits. Study guide for pilot students.
PAR (Precision Approach Radar) facilities at some joint-use and military airports can monitor your instrument approach and provide radar advisories as a backup to your primary navigation aid (ILS, VOR, etc.).
This service is provided automatically when:
- Weather is below VFR minimums (1,000 ft ceiling and 3 SM visibility)
- It's night
- The pilot requests it
Key limitations:
- Only available when the PAR final approach course coincides with the navaid's final approach course
- Only during PAR operational hours
- Advisories are secondary — your selected navaid is primary
Before final, you'll get the advisory frequency. If radar advisories aren't available, you'll be told. Advisories include:
- Notification of passing the FAF inbound (nonprecision) or OM/fix in lieu inbound (precision)
- Trend advisories on azimuth and (for precision approaches) elevation
- Glidepath info only for precision approaches like ILS — not for nonprecision, since descent profiles don't match the PAR glidepath
If you drift outside the PAR safety limit or deviate radically after repeated advisories, the controller will instruct a missed approach unless you have the required visual reference. Radar service ends automatically when the approach is complete.