The definition we (and the Technical Committee of the CE) give to “active warning device” is the following:
A: a device that gives a warning to the user, in case of an event, without the user having to do any effort to receive the warning
B: warning meaning: changing from one state to the other when going from OK to NOT OK
Criteria A: buzzer, light in front of the eye, … is ok
light or display clipped somewhere, so that the user must take action to look at it…not ok
Criteria B a PP02 indicator in front of the eye: not ok: as there is not change of state when the event occurs, and the memory will wipe out the signal after some time
A HUD where a light starts or goes out when the event happens, combined with flashes or whatever = ok as a “change in state” is noticed