According to reports, a Pakistan Navy maritime patrol aircraft observed a submarine on October 16 2021. The accompanying video shows two masts of a submarine. Analysis of the footage suggests that it is a Scorpène class submarine. Circumstantially, this supports the claim that it is an Indian Navy vessel, which operates the Scorpène, known locally as the Kalvari Class. Submarine expert Richard W. Stirn, who specializes in identifying submarines based on their masts, also identified it as likely a Scorpène Class boat.
Based on the coordinates overlaid on the imagery, the submarine was observed approximately 150 nautical miles south of Karachi. This places it well within international waters, but within Pakistan’s EEZ (exclusive Economic Zone).
The location is also about the same distance from the Indian Navy’s base at Okha, and south of the India-Pakistan land border. It is about 400 nautical miles from the larger naval base at Mumbai.
There have been a series of similar events in recent years. Generally the exact details are unclear and it is reported differently by each country. This footage appears to be distinct from previously released imagery. And the annotations on the imagery indicates that it was taken on October 16 between 23:18 and 23:36 hours. It is not clear whether this is local time, or universal time (known as Zulu). If Zulu, then it would be around 0400 hours locally.
The full context of the video is unclear however and it could, for example, be snorkeling for training purposes. It is legal for the Indian Navy submarine to be operating there, even conducting intelligence operations.
India operates four Kalvari Class submarines, with another two expected to join the fleet in the next few years. They are not equipped with AIP (air independent power), which would reduce the amount of time that they have to snorkel. This is termed the indiscretion rate. However there are plans to equip them with a locally design fuel-cell AIP in the future.
The follow on P75I class are expected to have AIP from the start, and will generally be larger and more stealthy. The Indian Navy’s nuclear submarine fleet will not have to snorkel at all.
There are currently 4 contenders for the P75I deal. These are the French Barracuda type, South Korean DSME-3000, Spanish S-80 Plus, and Russian Amur Class. As well as AIP they are expected to be armed with land attack and anti-ship cruise missiles.
The Pakistan Navy meanwhile already operates three AIP equipped submarines. Like the Kalvari class, these are French designed, but the older Agosta hull. They are fitted with the MESMA (Module d’Energie Sous-Marin Autonome) AIP system. And the Pakistan navy’s next class, an export variant of the Chinese Type-039 Yuan class, will also have AIP.