A killswitch is absolutely necessary for running a large scale to protect yourself,rig and others around you. Killer rc or a dynamite killswitch will do just fine. Also never trust a radios built in failsafe as it will not protect you from a battery dying, disconnecting or any other loss of voltage. 1 thing that was not mentioned is if a throttle servo goes out and sticks wide open as well. You should join largescaleforums.com and talk amongst other large scale owners.