The ATO has several classification levels for over 300 facilities that are based on numerous factors including traffic volume, complexity and sustainability of traffic. Facilities are monitored continuously for upward and downward trends to adjust staffing levels and provide the appropriate level of support.

• Level 12 facility
  Examples: New York Center, Memphis Center, Potomac TRACON, Atlanta TRACON, Charlotte/Douglas Intl Tower, Chicago O’Hare Tower

• Level 11 facility
  Examples: Houston Center, Kansas City Center, Minneapolis TRACON, Las Vegas TRACON, Phoenix Sky Harbor Tower, Los AngelesIntl Tower

• Level 10 facility
  Examples: Albuquerque Center, Seattle Center, Salt Lake City TRACON, St. Louis TRACON, San Antonio Intl Tower, Pittsburgh Intl Tower

• Level 9 facility
  Examples: San Juan CERAP, Anchorage TRACON, Portland TRACON, Port Columbus Intl Tower, Daytona Beach Intl Tower

• Level 8 facility
  Examples: Tucson TRACON, Chicago Midway Tower, Atlantic City Intl Tower, Will Rogers World Airport Tower, Van Nuys Tower

• Level 7 facility
  Examples: El Paso Intl Tower, Fort Wayne Intl Tower, East Texas Regional Tower, Grand Forks Intl Tower

• Level 6 facility
  Examples: Andrews AFB Tower, Duluth Intl Tower, Sacramento Intl Tower, Flying Cloud Tower

• Level 5 facility
  Examples: Ann Arbor Municipal Tower, Great Falls Intl Tower, Juneau Intl Tower, Grand Canyon National Park Tower

• Level 4 facility
  Examples: Columbus Metropolitan Tower, Purdue University Tower