The boundary stratum of an ARTCC feature, derived from NASR ARB_SEG
ALTITUDE and TYPE columns.
Each ARTCC publishes its boundary geometry separately for each stratum,
because the lateral extent varies with altitude tier and oceanic boundary
type. The values here are the union of distinct stratum kinds observed
across all US centers:
LOW - domestic low-altitude stratum (typically SFC to FL180)
HIGH - domestic high-altitude stratum (typically FL180 to FL600)
UTA - Upper Control Area, used only by ZOA (typically FL600 and above)
The boundary stratum of an ARTCC feature, derived from NASR ARB_SEG
ALTITUDEandTYPEcolumns.Each ARTCC publishes its boundary geometry separately for each stratum, because the lateral extent varies with altitude tier and oceanic boundary type. The values here are the union of distinct stratum kinds observed across all US centers:
LOW- domestic low-altitude stratum (typically SFC to FL180)HIGH- domestic high-altitude stratum (typically FL180 to FL600)UTA- Upper Control Area, used only by ZOA (typically FL600 and above)CTA- oceanic Control AreaFIR- oceanic Flight Information RegionCTA/FIR- combined oceanic CTA and FIR boundarySet to
nullfor non-ARTCC features.