Portuguese patrol aircraft detects Russian submarine in Baltic sea

Advanced equipment installed on the Portuguese reconnaissance and patrol aircraft designed for anti-submarine warfare, the P-3C Orion, enabled the detection of a Russian submarine in the Baltic Sea. According to Russian media, it was most likely the B-608 Mozhaysk belonging to the Baltic Fleet. What kind of submarine is it?

The submarine was spotted in the Baltic Sea at the end of June. As reported by the Bulgarian Military, the vessel was not in combat mode. It was on the surface, which made the task significantly more accessible for the pilots of the Portuguese P-3C Orion. The service also reminds us that submarines like the B-608 Mozhaysk must surface at least once daily due to their air-dependent propulsion system. At such times, they become vulnerable to detection by conventional radars, optoelectronic reconnaissance systems, or AESA radars.

The B-608 Mozhaysk is a Project 636.3 (06363) Varshavyanka-class submarine based on the Soviet Project 877 submarine. It has a length of 73 metres and a width of about 10 metres. It displaces nearly 3470 tonnes when submerged. The vessels are unofficially called "acoustic black holes" due to their low noise levels.

The Russians have managed to minimise the acoustic signature parameters in these submarines. Introduced modernisations have also improved target detection capabilities, enabling them to carry modern armaments. Varshavyanka-class submarines can carry Kalibr missiles.

It is worth mentioning that Kalibr is a Russian weapons system consisting of anti-ship cruise missiles, cruise missiles intended for land targets, and rocket torpedoes for anti-submarine warfare. It has standard vertical launch system launchers. In addition to Kalibr missiles, Project 636.3 submarines are equipped with six torpedo tubes and—in total—18 torpedoes of 533 millimetres calibre.