ECDIS backup arrangement

An ECDIS backup arrangement is the independent secondary means of navigation that SOLAS Chapter V requires whenever ECDIS is the primary chart system, so a single failure does not leave the ship without charts. It must take over the navigational function within the time needed to keep the ship safe during the takeover, drawing position from a separate sensor feed and power from an alternative supply. In practice it is a second type-approved ECDIS on independent power and an independent GNSS input, which lets a ship run paperless; an appropriate folio of paper charts is the other accepted option. The arrangement is checked at survey under SOLAS V/19.