An Air Route Traffic Control Center (ARTCC), or simply a "center", handles aircraft flying between airports across a large region, mostly at higher altitudes. Twenty centers cover the contiguous United States, each named for a city and known by a three-letter code starting with Z: ZNY is New York Center and ZFW is Fort Worth Center.
Towers, approach controls and centers
- Tower: runways and the airspace right around one airport.
- TRACON (approach and departure): the busy airspace within roughly 30–50 miles of major airports.
- Center (ARTCC): everything in between, including the high-altitude routes airliners cruise on.
Why departures are held in other cities
When the FAA issues a ground stop, it lists which centers' airports are included: the departure scope. Flights from airports in those centers to the affected airport are held; flights from farther away may still depart, because they'll take long enough to arrive that the problem may have cleared.
Scopes are often described in tiers: the airport's own center, plus the first tier of neighboring centers, plus sometimes the second tier beyond that. A severe or long event may include every center ("ALL") and even Canadian airports. So a thunderstorm at Dallas/Fort Worth can keep you at the gate in Chicago, because Chicago Center (ZAU) is included in the scope.
On the live map, select an active ground stop to see its held centers light up, with flow lines into the airport.
All centers
- Albuquerque Center (ZAB)
- Anchorage Center (ZAN)
- Chicago Center (ZAU)
- Boston Center (ZBW)
- Washington Center (ZDC)
- Denver Center (ZDV)
- Fort Worth Center (ZFW)
- Honolulu Control Facility (ZHN)
- Houston Center (ZHU)
- Indianapolis Center (ZID)
- Jacksonville Center (ZJX)
- Kansas City Center (ZKC)
- Los Angeles Center (ZLA)
- Salt Lake City Center (ZLC)
- Miami Center (ZMA)
- Memphis Center (ZME)
- Minneapolis Center (ZMP)
- New York Center (ZNY)
- Oakland Center (ZOA)
- Cleveland Center (ZOB)
- Seattle Center (ZSE)
- San Juan Center (ZSU)
- Atlanta Center (ZTL)