Safety Of Life At Sea - This International Convention is the most important treaty protecting the safety of merchant ships. It divides all vessels in 2 groups: SOLAS and non SOLAS vessels. SOLAS vessels need to comply with GMDSS sattelite and radio equipment carriage requirements. SOLAS vessels are all cargo ships of 300 GRT and upwards and all passenger ships with some exceptions. Detailed SOLAS vessels definition may be found in ALRS Volume 5. Non SOLAS vessels do not need to comply with GMDSS radio equipment carriage requirements, but will increasingly use it, because that causes an important increase of the safety at sea. Some countries have incorporated GMDSS radio equipment carriage requirements into their domestic marine legislation that is valid for non SOLAS vessels under their flag.