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Forgive my total lack of aviation knowledge. I just flew out of SFO and was fascinated by the fact that pairs of planes alternated between departing on 28L + 28R (simultaneously) and arriving on 19L/R.

My question is this: What amount of micromanagement from ATC exists to keep taking-off planes on schedule and not running into the landing planes, especially in cases where runways cross? How much information does the tower give to the taxiing planes?

Thanks!

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  • $\begingroup$ To paraphrase a much older comment about how some piece of technology works: "Very well, thank you". Alternately, the same way one would get to Carnegie Hall ("Practice, Practice, Practice"). $\endgroup$ – Aaron Dec 31 '13 at 1:54
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Chapter 9 - Departure Procedures and Separation of the FAA Order titled "Air Traffic Control" covers the procedures that are used for aircraft departures, including those cases where they have intersecting runways.

There are numerous procedures that they follow that are specific to intersecting runways, including:

  • 3-9-4 - LINE UP AND WAIT (LUAW)
    • If the tower has an airplane Line Up And Wait (taxi onto the active runway but not actually takeoff) because of another airplane that is landing or taking off on an intersecting runway, they must inform them of the other airplane and why they are not taking off.
  • 3-9-7 - WAKE TURBULENCE SEPARATION FOR INTERSECTION DEPARTURES
  • 3-9-8 - INTERSECTING RUNWAY SEPARATION
    • This probably covers most of what you are asking about, and has some great pictures showing when they are allowed to clear another airplane for takeoff in different situations. For instance, they can't clear an airplane for takeoff with another airplane landing on an intersecting runway until after they have passed their runway.

Note that there are similar procedures in Chapter 10 - Arrival Procedures and Separation

In short, there are lots of extra procedures that must be followed when using intersecting runways simultaneously, but they also get a lot of operational benefits when they can do it so are able to get a lot more airplanes on and off the ground in the same amount of time.

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As mentioned, there are lots of procedures that can be used. The one I am most familiar with (from a GA standpoint) is Land And Hold Short Operation (LAHSO). In this case, ATC may sequence you in on a runway and then ask you if you can preform a LAHSO (this happened to me last week actually).

The basic procedure is to land and stop the aircraft before the runway intersection, so that the other runway can remain in use since, in theory, you won't cross it. Keep in mind that this is dependent on the aircraft and airport in question considering the landing distances that are required.

For the record, I was flying a Piper Warrior and landing at Northeast Philadelphia Airport (KPNE) on runway 33 (length: 5000 feet) and the intersection with 6/24 is far off at the other end making the maneuver quite easy.

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