Safety Of Life At Sea - This International Convention is the most important treaty protecting the safety of merchant ships. It divides all vessels into 2 groups: SOLAS and non-SOLAS vessels. SOLAS vessels need to comply with GMDSS satellite and radio equipment carriage requirements. SOLAS vessels are all cargo ships of 300 GT and upwards and all passenger ships, with a few 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 it causes an important increase in 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.