A safety device for controlling an engine includes a first and a second sensor of an environmental parameter, two channels for processing data measured by the sensors, each of the channels each including a command module and a power supply. The device includes at least two relays. The first relay is capable of receiving a first command coming from a supply and delivering, in the absence of the first command, data from the first sensor to the second command module. The second relay is capable of receiving a second command coming from the supply and delivering, in the absence of the second command, data from the second sensor to the first command module. The supply of the active channel sends a command to the relay associated with it, the relay sending data from the sensor to the active channel.