What does “DISTRESS” signal mean?

Distress signal :-

The distress signal mayday indicates that a ship, aircraft or other vehicle is threatened by grave or imminent danger and require immediate assistance.

Distress alert :-

The transmission  of distress alert in GMDSS indicate a ship or aircraft or any other vehicle or other person is threatened by grave and imminent and requires immediate assistance.

The Radio telephone distress procedure consist of :-

1. The alarm signal (whenever possible) followed by
2. The distress call
3. The distress message with full implementation of GMDSS in Feb 1999.

The automatic alarm device used on 2182 Khz are no longer required.