* Click on CENTER for graphical tier information
SIX WESTZAB / ZDV / ZLA / ZLC / ZOA / ZSE
TEN WEST ZAB / ZDV / ZFW / ZHU / ZKC / ZLA / ZLC / ZMP / ZOA / ZSE
TWELVE WEST ZAB / ZAU / ZDV / ZFW / ZHU / ZKC / ZLA / ZLC / ZME / ZMP / ZOA / ZSE