What does man-down mean?

Man-down is a tilt-switch inside the radio that automatically sends an alarm signal if the radio is tipped on its side for more than a pre-set period that can be configured at the time the radio is supplied. The radio usually beeps to warn the user that the alarm signal will be sent if the radio is not positioned upright again.

The purpose of the ‘man-down’ feature is to protect lone workers, so if someone was to fall over incapacitating them, their radio would send out an alarm warning other users or the control centre, who can then send for help.