Yesterday the Finnish MoD announced that the RIM-162 Evolved SeaSparrow Missile (ESSM) has been chosen as the main air defence weapon for the upcoming Pohjanmaa-class corvettes.

The DSCA cleared the ESSM for export already a year ago, and crucially this was for the quad-packed Mk 25 launcher. This is fitted into the Mk 41 VLS launch system, which is a module of eight box-shaped shafts in which the missiles are stored until launch. The Pohjanmaa-class will be the smallest operational vessel fitted with the system by some margin (Taiwanese test bed LCC-1 Kao Hsiung is roughly same size), and interestingly enough it seems the full strike-length cells will be fitted.

This will give the corvettes a total of 32 ESSM per vessel (the astute observer will notice that the DSCA request only cover 68 missiles, meaning that further orders are to be expected), a significant upgrade in both range and numbers compared to the Hamina-class. While the Hamina’s Umkhonto have an IR-seeker, the ESSM have a passive radar seeker, which gives better performance in bad weather. When it comes to active versus passive radar seekers, unlike the situation in air-to-air combat where requiring the launching platform to keep it’s radar on target conflicts with the need to evade incoming fire, on a surface ship it isn’t necessarily as much of a problem as the radar stays active in a 360° search sector throughout the engagement.

Range is another major factor. The increase in range from 12 to 50 km gives a 17 times greater theoretical area covered. It has also been announced that the vessels, both as sensors and as shooters, will be integrated as part of the joint air defence network of the Finnish Defence Forces. This will give a significant boost to the air defences around the southern coastline, a key area for the country due to its concentration of population centres, ports, and heavy industry. This would be of particular importance in the early stages of a conflict, where the ground based systems of the Army might not have had time to deploy in the field.

The Mk 41 also allows for significantly larger missiles to be used, including the Standard-family of the US Navy and land-attack weapons such as the TLAM. However, with only eight available cells per corvette, swapping out a quad-pack of ESSM for a single longer-ranged SAM has serious effects on the ability of the vessel to fend off prolonged attacks. The Mk 41 could be used as a platform for missile defences to target systems such as the Iskander. E.g. Denmark is planning on doing this, but this would effectively tie up our limited number of corvettes in point defence missions along the southern shore.

An important factor in the choice was likely the widespread use of the Mk 41 and ESSM-combination, which ensure the ability to quickly fill up stocks if the need arises (i.e. we can hopefully get more missiles from US or even Norwegian stocks if we get dragged into a war).

The choice of ESSM will also have indirect effects on the Army’s GBAD program for a medium-range SAM-system. The inability of MBDA to secure a naval CAMM-order from Finland will likely impact the chances for the same missile on land as well. The NASAMS-compatible AMRAAM-ER in turn got a further boost, as it share some parts commonality with the ESSM (the ESSM can also be fired from the NASAMS launcher, though it is dubious if the Army wants a passive seeker head). Overall, MBDA has had a surprisingly hard time in securing any kind of orders in Finland. Time will tell if HX changes this.

On a final note, it is nice to finally see the MoD and Navy fully switch to referring to the vessels as the Pohjanmaa-class. The name has been known for quite some time, and in building a connection between the general public and the project it certainly has a nicer ring to it than the formal Squadron 2020.