Abstract: Impact at a headpiece, for example a protective helmet, is characterized in part using an impact sensor including at least one acceleration switch positioned on the helmet. A microcontroller is configured to identify and store acceleration switch opening duration data based on the binary output values of the at least one acceleration switch. A processor at a portable electronic device receives the acceleration switch opening duration data and determines whether the experienced impact force is associated with an impact force magnitude that is within a predetermined head injury range of magnitude. An impact alert is generated when the impact force magnitude is within the predetermined head injury range of magnitude. In an embodiment, the portable electronic device displays a severity indication and an identifier of a person associated with the sensor that experienced impact.