How come it is safe and legal to land in parallel runways (for example, in SFO).

The planes are way too close, at a distance that would not, I assume, be according to flight regulations and safety rules during cruise flight.

At what distance from airport or below what altitude becomes it ok to fly like this?

Can airplanes also take off in parallel, or only land?

  • $\begingroup$ also related: aviation.stackexchange.com/questions/9361 aviation.stackexchange.com/questions/3649 $\endgroup$
    – Federico
    May 13, 2015 at 6:11
  • 1
    $\begingroup$ Frankly, you could make a decent argument that SFO's parallel runway operation isn't particularly safe. It's not like the FAA set criteria for SOIA and parallel visual approaches and SFO was built to match those requirements; SFO was built with runways 750' apart and the rules were set based on that. But safety is not a yes/no question, it's a matter of degree. We've all decided to accept the additional risk, which is managed through special procedures and training, in exchange for allowing SFO to handle a reasonable volume of traffic (since building an additional runway is near-impossible). $\endgroup$ May 13, 2015 at 7:12
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    $\begingroup$ Simultaneous Independent and Dependent Parallel Instrument Approaches - 6.2.2 Target Level of Safety : "The target level of safety (TLS) used for simultaneous approaches was no more than one fatal accident per 25 million approaches" $\endgroup$
    – mins
    May 13, 2015 at 7:39
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    $\begingroup$ Not a duplicate: "is this practice safe/wise" is a different question than "what is the regulatory minimum distance." Voting to reopen. $\endgroup$
    – Ralph J
    May 13, 2015 at 9:09
  • $\begingroup$ I agree, this is a different question and not a duplicate. I’d like to re open as well. $\endgroup$
    – Murph
    Oct 15, 2021 at 18:00

1 Answer 1


Whether Parallel Runway Operations are allowed at an airport is dependent on many factors, such as:

There is two modes that are interesting here, which is the full parallel mode, where lateral separation is no longer required once both aircraft are established in the precision approach and staggered mode, where the runways are too close for parallel mode and need to maintain 2.5 NM lateral separation during the approach phase.

The same regulations apply to departures, you can read about it in EUROCONTROL's SkyBrary.

Related questions:
How are go-arounds safe with parallel runways?


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