Sometimes what we do in New York is Call-for-Release (CFR). If I’m the TMU for the event, I’ll usually be asking ZBW—or at the very least, BOS—for CFR for all flights coming to the designated airport. That way, I can look for appropriate gaps in enroute/arrival flow to fit in aircraft. Downstream centers can do this too; for instance, often times we get a heavy arrival stream from ATL at some point during the event. ZTL is a tier 2 center and admittedly, we have very little infrastructure to communicate with them so we ask ZDC to have them either provide MIT, reroutes, or ideally, CFR to either our TRACON, Center, or just between them (ZTL to ZDC).
Additionally, we have implemented CFR for ZOB and CZY, where Toronto traffic is heavy.
CFR is pretty much as close as we can get to using all available arrival capacity efficiently without creating excessive delay through ground stops and holding. All that has to happen is the tower calls either an enroute controller or the TMU requesting CFR and asks for a release time. They have 2 minutes before the time and 1 minute after the time to release that aircraft or else they will have to ask for another time.
Alternatively, if you know the demand before an event (like through signups where you have a flight list), you can construct a ground delay program to schedule aircraft. This is the most effective method of controlling your arrival rate because it restricts it to a certain number. You break each hour into segments and schedule aircraft to each block leaving a certain number of slots empty to account for unscheduled traffic (pop ups). Unfortunately, while often being the most effective method of controlling your arrival rate, it is the most time consuming and relies on a high level of controller-controller and controller-pilot cooperation and rarely ever suits events in VATSIM due to the lack of that cooperation.
Finally, for short term periods of excess demand, a ground stop is usually sufficient. The scope is important here and must be determined before implementing the GS. If there is excess demand for MSP and much of the future traffic isn’t airborne yet and originated from ORD, MDW, and MCI, then a tier 1 ground stop would suffice. If you have a heavy arrival stream from DEN and there are 28 more departures not yet airborne, bound to MSP, then a single-airport (for DEN) is all that’s needed and anything more than that would generate excess delay. If there is excess demand from many ARTCCs, all scheduled into MSP and not yet airborne, then an ALL+Canada GS might be most effective.
Oh, and for reference, there have been times where 40 MIT for ZTL to ZDC wasn’t even enough for spacing LGA arrivals and we had to seek other solutions. One thing we did was implement a mandatory reroute from the FAA Playbook that swapped the arrivals to come through ZOB and this alleviated congestion some. ZDC also did a great job in creating space for us while that was happening. If I remember correctly, BOS didn’t have a whole lot of traffic coming in so nothing was necessary with them, though if it were a problem, I would’ve had them on CFR.
