This page provides an overview of the PRM system. For details of individual company requirements for PRM, pilots are strongly encouraged to consult AIP and their company operations manuals.
The Precision Runway Monitor (PRM) is a highly accurate air traffic surveillance system designed to maximise air traffic flow to parallel runways during periods of inclement weather. PRM allows qualified pilots to accept reductions in lateral separation standards during ILS approaches to parallel runways separated by less than 1,525 metres.
At the heart of the system is a high resolution radar providing a very fast update rate for display to a specialist PRM Controller monitoring each approach.
A ‘No Transgression Zone’ (NTZ) with a width of 610 metres is established between the parallel approach paths to provide for a suitable safety buffer between aircraft on adjacent ILS approaches.
Without PRM, ATC is required to apply a 2NM stagger separation between aircraft on adjacent ILS approaches. With PRM, aircraft can be processed independently of any traffic on the adjacent approach track. Separation is assured by requiring any aircraft that deviates significantly from the approach track to immediately turn away from the adjacent approach path. Affected aircraft on the adjacent approach will also be turned away immediately.
The specialised controller interfaces will alert ATC to any tendency an aircraft may have to deviate towards the adjacent centreline. In this event the PRM Controller will advise the pilot of the deviation. A “No Transgression Zone” (NTZ) with a width of 610 metres is established between the parallel approach paths to provide a suitable safety buffer between aircraft on adjacent ILS approaches. If an aircraft is observed to penetrate the NTZ, a “Breakout” procedure will be initiated immediately by the PRM Controller and both that aircraft and any conflicting aircraft on the adjacent approach will be turned away.
To take advantage of the PRM system, pilots must familiarise themselves with the procedures to be used. An infringement of the NTZ does not allow any time for confusion or indecision on the part of the pilots or controllers. Breakout instructions require an immediate response.
A thorough cockpit briefing between crew members well in advance of commencing the approach is an essential part of an ILS PRM approach. All flight crew members must be thoroughly familiar with the approach, the procedures required for the aircraft they are flying and most importantly, the procedures to be followed in the event of a breakout.
Pilot Requirements: before conducting a simultaneous close parallel ILS PRM approach, Australian-registered pilots or pilots of Australian-registered aircraft must have completed training approved by CASA including:
- Viewed the Airservices Australia video “ILS PRM Approaches – A Pilot’s Approach“.
- Be thoroughly familiar with the ILS PRM approach procedures in AIP DAP, or equivalent operational documents.
- Familiarisation with the breakout procedure and phraseology.
- Completion of an examination conducted by:
- the operator’s training and checking organisation, or
- chief pilot holding instrument rating renewal approval, or
- flying training school holding instrument training approval.
Foreign-registered pilots or aircraft must be approved by their National Aviation Authority to conduct ILS PRM approaches.
Pilots who complete the training through an approved flight training school must obtain a log book endorsement by that training organisation.
Simulator training in breakout procedures is not mandatory but is strongly recommended, particularly in aircraft fitted with automated flight guidance systems.
If unable to participate in an ILS PRM approach, pilots must notify ATC prior to 120 DME SY (or if departing from within 120 DME SY on first contact with ATC).
Pilots who are not ILS PRM qualified will be cleared for a standard ILS approach and ATC will apply dependant separation standards between aircraft.
While ILS PRM approaches are in use, aircraft able to comply will be afforded priority over non-compliant aircraft.
ATIS: The ATIS will include notification when ILS PRM approaches are in use.
Approach Plates: Separate approach charts have been issued specifically to be used for ILS PRM approaches.
Dual VHF Requirements: Dual VHF equipment is required. The two receivers to be used must have volumes set to the same level. One radio will be set to the tower frequency and the other radio to the PRM frequency. The tower controller and the PRM controller will broadcast on both frequencies with the PRM Controller possessing communication override. Pilots must not transmit on the PRM frequency.
Communications from pilots with the tower controller will be conducted on the tower radio frequency only. A “breakout” instruction would be issued by the PRM controller on both frequencies. In the event of frequency congestion or over-transmission on the tower frequency, the pilot will still hear the breakout instruction on the PRM frequency.
Hand Fly a ‘Breakout’: Pilots issued with “Breakout” instructions are in a situation of minimal lateral separation with another aircraft with little or no advance warning of impending breakout. Time is critical. Simulation studies have consistently demonstrated that to obtain the quickest response, all “Breakout” procedures must be hand flown. In unusual circumstances, descending breakout instructions may be given but this will not be an altitude below the minimum vectoring altitude (MVA).
A breakout is a different procedure entirely to a missed approach procedure. Unlike a missed approach, pilots will be given instructions on breakout that will not conform to a standard track or level. Pilots will be instructed to turn immediately, climb or descend to routes and levels that maintain traffic and terrain clearance.
In implementing PRM in the runway 16 direction at Sydney, Airservices, has provided assurance that it will, consistent with the overriding concern for air safety, take action to limit the northern extent downwind leg and to minimise the length of time that aircraft maintain 3000ft. Controller training is designed to meet these objectives. It is essential that aircrew are aware of these objectives and assist by bearing in mind the following factors:
Descent profile should be maintained in accordance with the distance to run to touchdown or the ‘base turn’ point notified by ATC.
On a right circuit for a PRM approach to runway 16R, aircraft cannot be turned onto the base leg until they are at or near 3000ft. Likewise, a right circuit to runway 34R requires aircraft to be near 2000ft before a base turn. Controllers will provide information to pilots on the distance to run to the ideal base turn point.
Pilots are strongly advised to reference company operating procedures but the following instructions will serve as a guide to aircraft operating procedures.
Abbreviated Checklist Prior to Commencing Approach
ILS PRM Approach Plate – Selected
Brief for Approach and Breakout – Complete
VHF Frequencies – COM I – Set to Tower
VHF Frequencies – COM 2 Set to PRM Frequency (Monitor only)
Two radio procedures are specific to PRM. These relate to observed localiser course deviations and NTZ penetrations (Breakouts):
The ILS PRM display and radar technology allows for aircraft track projections up to 10 seconds in advance of the actual aircraft position. If the PRM display indicates that an aircraft will penetrate the NTZ an advisory broadcast will be issued to the aircraft. The phraseology will be:
“(callsign), radar indicates you are deviating (left/right) of the localiser course.”
Note: Pilots are not required to acknowledge this deviation advice.
ATC is required to issue instructions to break off the approach to any aircraft that enters the NTZ. Any aircraft in conflict on the approach to the adjacent runway will also be turned away. Phraseology for the Breakout will be as follows:
“Breakout alert, (callsign), turn (left/right) immediately heading (…). Climb/descend to (altitude).”
PRM offers a safe and practical way to maintain airport capacity using parallel runways when the weather conditions do not permit the use of Independent Visual Approaches.