We have a department that has a small 10 sq mile 1st due area, then we have a contract with the major municipality to cover a good part of that area as "closest unit" and then we have a fairly large mutual aid agreement.

So when defining our response area, what do I define it as.... Just our first due, or a combination of all the above? At least 1/2 our calls are on contract, maybe 1/5 are mutual aid and the rest are first due.