See the “ILS Approaches” paragraph above for information about pilot responsibilities when simultaneous approaches are in use.

[Figure 4-46] When simultaneous dependent approaches are provided, ATC applies specific minimum diagonal separation criteria, depending on the runway separation, between aircraft on adjacent final approach courses. Aircraft will be staggered by a minimum of 1 NM diagonally on final, depending on the distance between runway centerlines. Greater separation standards are applied when the distance between runway centerlines is greater. [Figure 4-43]

At some airports, simultaneous dependent instrument approaches can be conducted with runways spaced less than 2,500 feet with specific centerline separations and threshold staggers. ATC is permitted to apply reduced diagonal separation and special wake turbulence procedures. The lead aircraft of the dependent pair is restricted to being small or large aircraft weight type and is cleared to the lower approach. The design of the approach, aircraft weight type, and lateral separation between the two approaches provide necessary wake turbulence avoidance for this type of operation. An example of approach design to help avoid wake turbulence is that some locations use different glide slope angles on adjacent approaches; also, if applicable, staggered thresholds help. An ATIS example is: “Simultaneous ILS Runway 28 Left and ILS Runway 28 Right in use.” For further information, see FAA Orders JO 7110.65 and JO 7110.308.

Where a simultaneous approach operation is approved, sometimes each approach chart indicates the other runway(s) with which simultaneous approaches can be conducted. For example, “Simultaneous approaches authorized with runway 12L”. As procedures are revised, the chart note will be modified to indicate “Simultaneous approach authorized” but will not list the other runways or approach types as that detailed information will normally be transmitted in the ATIS or by ATC. For example, pilots flying into Sacramento, California, may encounter parallel approach procedures. [Figure 4-44] When there is no chart note stating, “Simultaneous approaches authorized”, standard separation is used between aircraft on parallel

Dual and triple simultaneous independent parallel instrument approaches, are authorized at certain airports with specified distances between parallel runway centerlines. As a part of the simultaneous independent approach approval, an NTZ must be established to ensure proper flight track boundaries for all aircraft. Outside of the NTZ, normal operating zones (NOZ) indicate the operating zone within which aircraft remain during normal approach operations. The NOZ between the final approach courses varies in width depending on the runway centerline spacing. The NTZ is defined as a 2,000-foot wide area located equidistant between the final approach courses in which flight is not allowed during the simultaneous operation. [Figure 4-46] Any time an aircraft breaches or is anticipated to breach the NTZ, ATC issues instructions for the threatened aircraft on the adjacent final approach course to break off the approach to avoid potential conflict.

A local controller for each runway is also required. Dedicated final monitor controllers for each runway monitor separation, track aircraft positions and issue instructions to pilots of aircraft observed deviating from the final approach course. [Figure 4-45] These operations are normally authorized for ILS, LDA and RNAV approach procedures with vertical guidance. For simultaneous parallel ILS approach operations, pilots should review the chart notes to determine whether the non-precision LOC procedure is authorized (in the event of glide slope equipment failure either in the aircraft or the ground). An example of a restriction on the use of a LOC procedure is shown in the notes on Figure 4-24: “LOC procedure NA during simultaneous operations”. Likewise, for RNAV (GPS) approaches, use of LNAV procedures are often restricted during simultaneous operations.

Triple simultaneous independent approaches are authorized provided the runway centerlines are separated by at least 3900 feet for triple straight in approaches. If one or both outside runways have an offset approach course of 2.5° to 3.0°, the spacing between those outer runways and the center runway may be reduced to 3000 feet.

Simultaneous close parallel (independent) PRM approaches are authorized for use at designated airports that have parallel runways spaced less than 4,300 feet apart. [Figure 4-47] Certain PRM approaches are referred to as Simultaneous Offset Instrument Approaches (SOIA) and are discussed in depth later in this chapter.

PRM procedures are the most efficient method of increasing approach capacity at airports with closely spaced, parallel runways. Use of PRM procedures increases airport capacity during periods of low visibility by providing ATC the capability to monitor simultaneous close parallel (independent) approaches. These PRM operations reduce delays and increase fuel savings. Traditionally the PRM system included a high-update rate radar, a high resolution ATC radar display, as well as software that can autonomously track aircraft in close to real time, with visual and aural alerts that depict the aircraft’s current position and velocity as well as displaying a ten-second projected position to the controllers. Today, most PRM operations are conducted without the need for high update rate radar, so long as all of the other requirements to conduct such approaches are met.

There are also special communications and ATC requirements for PRM approaches. PRM approaches require a final NTZ monitor controller for each runway, a separate tower controller for each runway, a PRM tower frequency, and a runway-specific PRM frequency. Each final monitor controller will have a dedicated PRM frequency, and the tower controller will have a separate common PRM frequency. Pilots transmit and receive on the common tower PRM frequency, but maintain listening watch on the final controller’s PRM frequency for their specified runway. The final monitor controller has override capability on their PRM frequency. In that way, if the common tower frequency is blocked, the monitor controller’s instructions will be heard by the pilot on the monitor controller’s PRM frequency. Pilot training is prescribed and required for pilots prior to using the PRM procedures. The FAA PRM website (http://www.faa.gov/training_testing/ training/prm/) contains training information for PRM approaches and hosts PRM training materials for download or viewing online.”

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. Pilots who are unable to accept a PRM approach may be subject to delays.

The approach chart for the PRM approach requires review of the accompanying AAUP page, which outlines pilot, aircraft, and procedure requirements necessary to participate in PRM operations. [Figure 4-48] Pilots need to be aware of the differences associated with this type of approach. Differences, as compared to other simultaneous approaches, are listed below:

SOIAs allow simultaneous approaches to two parallel runways spaced at least 750 feet apart, but less than 3,000 feet. Traditionally, the SOIA procedure has used an ILS/PRM approach to one runway and an offset localizer-type directional aid (LDA)/PRM approach with glideslope to the adjacent runway. Now, RNAV (GPS) and RNAV (RNP) approaches may also be used for SOIA.” Approach charts will include procedural notes, such as “Simultaneous Close Parallel approach authorized with LDA PRM RWY 28R and RNAV (GPS) PRM X RWY 28R.” or “Simultaneous approach authorized”. San Francisco had the first published SOIA approach. [Figure 4-49]