Simultaneous Dependent Approaches

AIM ¶ 5-4-14 Simultaneous Dependent Approaches

AIM 5-4-14 explains simultaneous dependent approaches: parallel runway spacing, diagonal radar separation, and pilot procedures for ILS/RNAV/GLS approaches.

In Plain English

Simultaneous dependent approaches are an ATC procedure that allows aircraft to fly approaches to parallel runways with centerlines spaced from 2,500 to 9,000 feet apart. Unlike independent approaches, dependent approaches require staggered (diagonal) separation between aircraft on adjacent final approach courses and do not require radar monitoring.

Key diagonal radar separation minimums based on runway spacing:

  • 2,500–3,600 ft apart: 1.0 NM diagonal
  • 3,600–8,300 ft apart: 1.5 NM diagonal
  • 8,300–9,000 ft apart: 2.0 NM diagonal

On the same final course within 10 NM of the runway, 3 NM (or 2.5 NM in some cases) applies. During turn-on, 1,000 ft vertical or 3 NM is provided.

Approach navigation may use ILS, RNAV, or GLS. Although non-precision minimums may be charted, only procedures specifically authorized may be used (e.g., "LNAV NA during simultaneous operations" means vertical guidance is required). Pilots are informed via ATIS or ATC when parallel approaches are in use. At some airports, dependent approaches occur to runways closer than 2,500 ft, requiring vertical guidance and maintaining last assigned altitude until glideslope intercept. No special pilot training is required.

AIM Source Text
FAA AIM ¶ 5-4-14
5-4-14. 5-4-14. Simultaneous Dependent Approaches FIG 5-4-21 Simultaneous Approaches (Parallel Runways and Approach Courses) Simultaneous dependent approaches are an ATC procedure permitting approaches to airports having parallel runway centerlines separated by at least 2,500 feet up to 9,000 feet. Integral parts of a total system are ILS or other system providing approach navigation, radar, communications, ATC procedures, and required airborne equipment. RNAV equipment in the aircraft or GLS equipment on the ground and in the aircraft may replace the required airborne and ground based ILS equipment. Although non-precision minimums may be published, pilots must only use those procedures specifically authorized by chart note. For example, the chart note “LNAV NA during simultaneous operations,” requires vertical guidance. When given a choice, pilots should always fly a precision approach whenever possible. A simultaneous dependent approach differs from a simultaneous independent approach in that, the minimum distance between parallel runway centerlines may be reduced; there is no requirement for radar monitoring or advisories; and a staggered separation of aircraft on the adjacent final course is required. A minimum of 1.0 NM radar separation (diagonal) is required between successive aircraft on the adjacent final approach course when runway centerlines are at least 2,500 feet but no more than 3,600 feet apart. A minimum of 1.5 NM radar separation (diagonal) is required between successive aircraft on the adjacent final approach course when runway centerlines are more than 3,600 feet but no more than 8,300 feet apart. When runway centerlines are more than 8,300 feet but no more than 9,000 feet apart a minimum of 2 NM diagonal radar separation is provided. Aircraft on the same final approach course within 10 NM of the runway end are provided a minimum of 3 NM radar separation, reduced to 2.5 NM in certain circumstances. In addition, a minimum of 1,000 feet vertical or a minimum of three miles radar separation is provided between aircraft during turn on to the parallel final approach course. Whenever parallel approaches are in use, pilots are informed by ATC or via the ATIS that approaches to both runways are in use. The charted IAP also notes which runways may be used simultaneously. In addition, the radar controller will have the interphone capability of communicating with the tower controller where separation responsibility has not been delegated to the tower. NOTE- ATC will not specifically identify these operations as being dependent when advertised on the ATIS. EXAMPLE- Simultaneous ILS Runway 19 right and ILS Runway 19 left in use. At certain airports, simultaneous dependent approaches are permitted to runways spaced less than 2,500 feet apart. In this case, ATC will provide no less than the minimum authorized diagonal separation with the leader always arriving on the same runway. The trailing aircraft is permitted reduced diagonal separation, instead of the single runway separation normally utilized for runways spaced less than 2,500 feet apart. For wake turbulence mitigation reasons: Reduced diagonal spacing is only permitted when certain aircraft wake category pairings exist; typically when the leader is either in the large or small wake turbulence category, and All aircraft must descend on the glideslope from the altitude at which they were cleared for the approach during these operations. When reduced separation is authorized, the IAP briefing strip indicates that simultaneous operations require the use of vertical guidance and that the pilot should maintain last assigned altitude until intercepting the glideslope. No special pilot training is required to participate in these operations. REFERENCE- AIM, Para 5-4-16 , Simultaneous Close Parallel PRM Approaches and Simultaneous Offset Instrument Approaches (SOIA).
Oral Exam Questions a DPE Might Ask
Q1What is a simultaneous dependent approach and how does it differ from a simultaneous independent approach?
Per AIM 5-4-14, a simultaneous dependent approach is an ATC procedure to parallel runways with centerlines spaced 2,500–9,000 ft apart. Unlike independent approaches, dependent approaches allow reduced runway spacing, do not require radar monitoring or advisories, and require staggered diagonal separation between aircraft on adjacent final approach courses.
Q2How does ATC notify pilots that simultaneous dependent approaches are in use?
Per AIM 5-4-14, pilots are informed by ATC or via the ATIS that approaches to both runways are in use, and the charted IAP notes which runways may be used simultaneously. ATC will not specifically identify the operations as 'dependent' on the ATIS — for example, 'Simultaneous ILS Runway 19 right and ILS Runway 19 left in use.'
Q3If a non-precision minimum is published but the chart says 'LNAV NA during simultaneous operations,' what does that mean for the pilot?
Per AIM 5-4-14, the pilot must use vertical guidance and may not fly the LNAV (non-precision) line of minimums during simultaneous operations. Pilots should only use procedures specifically authorized by chart note, and when given a choice should always fly a precision approach whenever possible.
Related Paragraphs in AIM Chapter 5
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AIM 5-4-14 — Simultaneous Dependent Approaches