Simultaneous Close Parallel PRM Approach are independent approaches conducted to runways with centreline spacing of less than 4300 feet (1310m) but at least 3000' (915m). PRM is an acronym for the high update rate Precision Runway Monitor surveillance system which is required to monitor the No Transgression Zone (NTZ) for specific parallel runway separations used to conduct simultaneous close parallel approaches. PRM is published in the title as part of the approach name for Instrument Approach Procedures (IAP) used to conduct Simultaneous Close Parallel approaches. “PRM” also alerts pilots that specific airborne equipment, training, and procedures are applicable.
An overview of Simultaneous Close Parallel PRM approaches is provided in the following diagram.
Simultaneous Close Parallel PRM Approach (Source: FAA AIM)
Note that aircraft will be separated laterally or vertically prior to the beginning of the NTZ and that the NTZ monitoring continues past the missed approach point (MAP) to ensure aircraft separation in the event of simultaneous missed approaches.
Simultaneous close parallel ILS PRM approaches are depicted on a separate Approach Procedure Chart titled ILS PRM Rwy XXX (Simultaneous Close Parallel). Note that one or both of the ILS PRM approaches in a simultaneous close parallel operation may be substituted with RNAV PRM or GLS PRM approaches. Because Simultaneous Close Parallel PRM approaches are independent, the NTZ and normal operating zone (NOZ) airspace between the final approach courses is monitored by two monitor controllers, one for each approach course. Simultaneous Close Parallel PRM approaches must meet all of the following requirements:
- specific pilot training
- PRM in the approach title
- NTZ monitoring utilizing a final monitor aid
- publication of an Attention All Users Page (AAUP) as part of the IAP
- use of a secondary PRM communication frequency
One of the unique features of Simultaneous Close Parallel PRM Approaches concerns the "breakout" protocol. Because of the close proximity of aircraft on adjacent approaches, should an aircraft on approach blunder into the NTZ, it will be the aircraft on the opposite approach that will be given breakout instructions by ATC.
Pilots must complete special training before accepting a clearance for a simultaneous close parallel ILS PRM, RNAV PRM, GLS PRM or LDA PRM approach. Operators must be approved for Simultaneous Close Parallel PRM Approach procedures by their NAA. Commercial operators will detail the specific training requirements in their Company Operations Manual in accordance with their approved Operations Specification (Ops Spec) for PRM approaches. Non commercial operators must be familiar with the content of the FAA Aeronautical Information Manual (AIM) pertaining to PRM operations. As a minimum, the training must include viewing of the FAA video (or equivalent) ILS PRM AND SOIA APPROACHES: INFORMATION FOR GENERAL AVIATION PILOTS.
The final approach courses of Simultaneous Close Parallel Approaches are monitored by two monitor controllers, one for each approach course. The NTZ monitoring system consists of:
- high resolution ATC radar displays
- automated tracking software which provides
- aircraft identification
- aircraft position
- a ten-second projected aircraft position
- aircraft speed
- visual and aural NTZ penetration alerts
Attention All Users Page (AAUP)
Multiple PRM approach charts at the same airport have a single associated AAUP. This page must be referred to in preparation for conducting the approach. Bullet points are published summarising the PRM procedures which apply to each approach and these must be briefed as part of the approach briefing. The following information may be summarized in the bullet points or published in more detail in the Expanded Procedures section of the AAUP. Briefing on the Expanded Procedures is optional. Bullet points on the AAUP include:
- ATIS - When the ATIS broadcast advises ILS PRM approaches are in progress (or ILS PRM and LDA PRM approaches in the case of SOIA), pilots should brief to fly the ILS PRM or LDA PRM approach. If not qualified to flight PRM approaches, ATC must be advised.
- Dual VHF Communications Required - To avoid blocked transmissions, each runway will have two frequencies, a primary and a PRM monitor frequency. The tower controller will transmit on both frequencies. The monitor controller’s transmissions, if needed, will override both frequencies. Pilots will ONLY transmit on the tower controller’s frequency, but will listen to both frequencies. The pilots should not select the PRM monitor frequency audio only until instructed by ATC to contact the tower. The volume levels should be set about the same on both radios so that the pilots will be able to hear transmissions on at least one frequency if the other is blocked. This procedure ensures that critical breakout instructions are not missed.
- Breakouts - Breakouts differ from other types of abandoned approaches in that they can happen unexpectedly and at any point during the approach. A pilot that is directed by ATC to break off an approach must assume that an aircraft is blundering toward them resulting in Loss of Separation. Pilots must always initiate the breakout in response to an air traffic controller’s instruction and the breakout must be initiated immediately. The following points provide specific breakout protocols:
- Execution - to expedite the manoeuvre, breakout procedures must be hand flown
- ATC Instructions - directed breakouts will consist of a turn away from the NTZ to a specified heading and a climb or a descent to a specified altitude. A descending breakout will be directed only when there are no other reasonable options available, but in no case will the descent be below the minimum vectoring altitude (MVA) which provides at least 1,000 feet required obstruction clearance
- Phraseology - If an aircraft enters the no transgression zone (NTZ), the controller will breakout the threatened aircraft on the adjacent approach using the phraseology "(aircraft call sign) TURN (left/right) IMMEDIATELY, HEADING (degrees), CLIMB/ DESCEND AND MAINTAIN (altitude)"
- TCAS - Should a TCAS RA (resolution advisory) occur during a breakout manoeuvre, the pilot should react appropriately to the TCAS vertical guidance. However, in this situation, it is critical that the turn to the ATC assigned breakout heading is also executed
Airports Conducting Simultaneous Close Parallel PRM Approaches