Ops 3 is for first responder medical calls within the Charlotte city limits. Ops 4 is for first responder medical calls in the county. Even number ops channels 6-22 are for county fire incidents requiring a seperate channel (fires, large wrecks, training) and the odd channels 5-21 are overflow channels in the city for EMS crews ie when medical command gets a separate channel in Charlotte for a large fire or wreck. Single unit response for wrecks typically end up on Ops 4 but a unique channel can be requested.
CFD operates on their zone 1 channels B through K with overflow on the zone 2 talkgroups when needed.
For wrecks and fires with both city and county response, Meck Ops and CFD Ops are usually patched by Alarm.