In the latest terminal procedures packet dated April 22nd all San Francisco PRM approaches have been deleted. I haven't seen any notice from the FAA on the decommissioning and am curious what the reason is. Is there any official documentation on the decommissioning?


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    $\begingroup$ Not officially, but a friend there said the staggered approaches are good enough and require less staffing. $\endgroup$
    – StephenS
    Apr 29, 2021 at 4:52
  • $\begingroup$ @StephenS Do you or your friend know how often PRM approaches were used in the past? $\endgroup$
    – wbeard52
    Apr 29, 2021 at 11:42
  • $\begingroup$ Would be nice to mention what "PRM approaches" are. Have no idea (allthough I have good knowledge of general aviation). $\endgroup$
    – kebs
    May 1, 2021 at 21:10
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    $\begingroup$ @kebs PRM stands for Precision Runway Monitor. It is used for Simultaneous Close Parallel PRM Approaches and Simultaneous Offset Instrument Approaches (SOIA). $\endgroup$
    – Bianfable
    May 2, 2021 at 10:38
  • $\begingroup$ Thanks, also found WP link, added in question. $\endgroup$
    – kebs
    May 2, 2021 at 12:41

2 Answers 2


They didn’t use SOIA / PRM everyday pre covid. In fact, even though it was officially decommissioned recently, it’s been several years (2017 maybe EARLY 2018) since NorCal approach has even staffed the PRM scopes or run SOIA Ops. They would only need to staff it when the weather sucks. When a pilots are able to see each other, they are running sideby visual approaches to 28L/R. Some of the foreign heavies will get an ILS with their “pairing” Traffic being on a visual approach. So:

  1. they didn’t need it unless it was IFR.
  2. They need less staffing without it. The controllers have to open up two more scopes when running SOIA operations. The PRM monitor scopes. Without it, they need less bodies. Hence, less money the FAA has to spend.
  3. closely spaced parallel operations or “CSP” replaced SOIA. FAA order 7110.308 allows the controllers to run slightly staggered approaches to parallel runways. It used to require a 1.5 mile stagger. They got a waiver at SFO / NORCAL approach to run a 1.0 mile stagger between airplanes in the same “pair”. Making dual ILS approaches in full IFR conditions practically just as efficient as SOIA / PRM operations. So they don’t need it. Hope this helps!
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    $\begingroup$ Welcome to Av.SE! $\endgroup$
    – Ralph J
    Oct 13, 2021 at 4:06

PRM approaches require recurrent crew training, additional ATC personal (you monitor a PRM controller in addition to the tower controller), and don't increase efficiency into SFO or PHL (which decommissioned their PRM years ago) that much. Today's airports are being built with runways separated enough to allow simultaneous ILS approaches.

In short - Training cost + Personnel cost > operational savings.


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