A tilt or acceleration sensing apparatus and method that allows a tilt or acceleration sensing device of a vehicle to determine: 1) a maximum fall angle of the vehicle, regardless of the orientation of the vehicle and the vehicle's tilt sensor(s) to the incline; or 2) the downward acceleration of the vehicle. In one embodiment, a method of determining a maximum fall angle of a vehicle includes sensing tilt angles of two sensing axes of the vehicle relative to a horizontal reference plane and calculating the maximum fall angle of the vehicle based on the tilt angles. The apparatus and method may also include comparing the maximum fall angle to predetermined values and generating output signals when the maximum fall angle exceeds the predetermined values. In another embodiment, a method of determining when a vehicle is sliding downhill includes sensing the accelerations of three sensing axes.