Original Project 877 boats are equipped with Rubikon MGK-400 sonar system (with NATO reporting name Shark Gill), which includes a mine detection and avoidance sonar MG-519 Arfa (with NATO reporting name Mouse Roar).
De originale projekt 877 både er udstyret med Rubikon MGK-400 sonarsystemet (med NATO rapporteringsnavnet Shark Gill, som inkluderer den højfrekvente minesøgningssonar MG-519 Arfa (NATO navn: Mouse Roar).