When is a hand flare activated to attract attention?

 in case of emergency to attract the attentions of SAR Team/Helicuptor etc.

Hand flare is one of the Pyro Techniques onboard and is used only during the time of distress and the resuce team should be with in the hand flare vicinity

At the time of distress, a hand flare is activated in the dark/night to attract rescuers

the hand flare is activated in the dark to attract rescuers  

a life buoy is a floating ring that is been thrown to someone drowning to gain buoyancy and prevent from drowning