Simultaneous close parallel (independent) ILS PRM approaches are authorized for use at airports that have parallel runways separated by at least 3,400 feet and no more than 4,300 feet. [Figure 5-44 on page 5-54] They are also approved for airports with parallel runways separated by at least 3,000 feet with an offset LOC where the offset angle is at least 2.5 degrees but no more than 3 degrees. The offset LOC approaches are referred to as Simultaneous Offset Instrument Approaches (SOIA) and are discussed in depth later in this chapter.

The PRM system provides the ability to accomplish simultaneous close parallel (independent) ILS approaches and enables reduced delays and fuel savings during reduced visibility operations. It is also the safest method of increasing ILS capacity through the use of parallel approaches. The PRM system incorporates high-update radar with one second or better update time and a high resolution ATC radar

display that contains automated tracking software that can track aircraft in real time. Position and velocity is updated each second and a ten second projected position is displayed. The system also incorporates visual and aural alerts for the controllers.

Approval for ILS PRM approaches requires the airport to have a precision runway monitoring system and a final monitor controller who can only communicate with aircraft on the final approach course. Additionally, two tower frequencies are required to be used and the controller broadcasts over both frequencies to reduce the chance of instructions being missed. Pilot training is also required for pilots using the PRM system. Part 121 and 135 operators are required to complete training that includes the viewing of one of two videos available from the FAA through the Flight Standards District Office (FSDO) or current employer:

  • “RDU Precision Runway Monitor: A Pilot’s Approach.”
  • “ILS PRM Approaches, Information for Pilots.”

When pilots or flight crews wish to decline a PRM approach, ATC must be notified immediately and the flight will be transitioned into the area at the convenience of ATC. Flight crews should advise ATC within 200 NM of the landing airport if they are not qualified or not equipped to fly a PRM approach.

The approach chart for the PRM approach typically requires two pages and outlines pilot, aircraft, and procedure requirements necessary to participate in PRM operations. [Figure 5-45] Pilots need to be aware of the differences associated with this type of ILS approach:

  • Immediately follow break out instructions as soon as safety permits.
  • Listen to both tower frequencies to avoid missed instructions from stuck mikes or blocked transmissions. The final ATC controller can override the radio frequency if necessary.
  • Broadcast only over the main tower frequency.
  • Disengage the autopilot for breakouts because hand-flown breakouts are quicker.
  • Set the Traffic Alert and Collision Avoidance System (TCAS) to the appropriate TA (traffic advisory) or RA (resolution advisory) mode in compliance with current operational guidance on the attention all users page (AAUP), or other authorized guidance, i.e., approved flight manual, flight operations manual.

It is important to note that descending breakouts may be issued. Additionally, flight crews will never be issued breakout instructions that clear them below the MVA, and they will not be required to descend at more than 1,000 FPM.

Figure 5-45. St. Louis, Missouri, ILS PRM RWY 11.