A few minutes ago the Clark County Dept. of Aviation began its exercise at McCarran Airport which is done once every three years. The following talk groups are in use with more to come: 37168 and 36912 on the SNACC system for the DOA. TG 42224 the ARFF channel is also in use. If you have a copy of the Southern NV Radio Scanner Book you might look at page 15 (Dept. of Aviation talkgroups), page 15 (EMS talkgroups) as ten hospitals will be involved in actual transports. It's is good listening.