This depends on the situation.  On village calls our normal procedure is to roll Engine 3 (Sheldon Hose Co.) and L4 (Ladder-4) followed by other units as needed (E2, M5, E1).  If this call is a country call we roll either Engine 1 (Ellsworth Hose Co.) or Engine 2 (Hydrant Hose Co.) along with E3, M5 and TA-18 (Tanker).  Again it all depends on the situation, if we have an aircraft incident we always roll Engine 1 due to its automatic foam system, and the same goes for high rise and large building fires in which we roll Ladder-4 (Hunter Hook and Ladder Co.). For MVA's and CO calls we respond with M5 and E3.