From the complexity setting glossary
JFK is is nine miles from LGA, and LGA is fourteen miles from EWR. However JFK is eighteen miles from EWR. Additionally I know that LGA/JFK runway selection are heavily dependent on each other but I don't know if EWR is affected as much. I would assume yes, though.
So provided JFK and LGA are independently calculated to be within one FPL of each other, each facility's FPL is set to the higher one. Most likely this is true for EWR and LGA as well. For example, this could be true:
- EWR TCI is 10.
- LGA TCI is 11.
- JFK TCI is 10.
- Because EWR is a "metro tower complex" with LGA, and because EWR is within one level of LGA, EWR is set to an 11.
- Because JFK is a "metro tower complex" with LGA, and because JFK is within one level of LGA, JFK is set to an 11.
Now in the (made-up example) case where EWR is 11, LGA is 10, and JFK is 9, it shouldn't be true that JFK would commutatively be set to match EWR's 11, because EWR and JFK are too far apart to be considered part of the same metro tower complex. Instead JFK should be set to match LGA's independently calculated 10, while LGA would be set to 11 to match EWR. But I would not at all be surprised to hear that they just lump all three together and call it a day.
I'm not at work to check the real TCIs but if anyone is I'd be interested to see where they fall.