The installation of equipment and the implementation of PRM procedures offer opportunities for increased arrival efficiency by permitting simultaneous closely spaced operations to be conducted at airports where parallel runways are separated by less than 4300 feet, but a least 3000 feet. For closely spaced operations where the runways are less than 3400 feet apart, one ILS approach course must be offset from the other by between 2.5 and 3.0 degrees.
In SOIA operations, the spacing between the approach courses rather than the runway separation is used to determine the approach design. An offset LDA with glideslope is used in place of the offset ILS approach. At the point where the LDA and ILS courses converge to 3000 feet, an LDA MAP is established and the No Transgression Zone (NTZ) terminates. Between the LDA MAP and the runway threshold, pilots conducting the LDA approach maneuver to align with the extended runway centerline, while providing collision and wake turbulence mitigation from the leading ILS aircraft. Specific cloud ceiling requirements apply to SOIA operations.
To realize the full benefits of PRM, all pilots flying into an airport that conducts PRM approaches must be able to accept a clearance for the approach when these services are offered. Pilots are encouraged to support these operations by completing training as identified by the FAA.
Pilots who have completed initial PRM training are not required to undergo additional training, except as outlined in their Operations Specifications. However, pilots are reminded that each approach may have operational differences, and therefore they must review the "Attention All Users Page” for the airport of intended landing before conducting an ILS PRM or LDA PRM approach.
RNAV (GPS) PRM approaches are approved by the FAA as an alternate method to conduct a PRM approach when the ground based navigation aids are temporarily out of service, or at the discretion of the pilot. Pilots are reminded that if they desire to conduct an RNAV (GPS) PRM approach when ILS or LDA PRM approaches are being advertised on the ATIS, ATC must be advised and a clearance must be issued to conduct the RNAV approach.
ILS/PRM approaches are presently conducted at ATL, and DTW. ILS/PRM and LDA/PRM, SOIA approaches, are currently conducted at SFO.