Moskva Burning – Using the #wargame Harpoon V from admiraltytrilogy.com to assess the story

Update as of April 14, 4:30pm Eastern time. Reports from Russian state media now say Moskva sunk while under tow.

As I start writing this post, it is the day after the news broke that the Russian Navy cruiser Moskva either was struck by Ukrainian coastal anti-ship missiles or suffered an ammunition explosion and fire. Pending further developments, let’s assume for the purposes of this post that the ship was attacked. This allows me to look at the event through the lens of wargaming, specifically using the rules for Harpoon V: Modern Tactical Naval Combat 1955-2020 (designers Larry Bond & Chris Carlson, Admiralty Trilogy Group, 2021).

In the October 2006 issue (#31) of The Naval SITREP: The Journal of the Admiralty Trilogy Game System, the co-designers of Harpoon V assessed the anti-ship cruise missile (ASCM) attack on the INS Hanit in July 2006. I’m not going to go into the same technical depth here but instead want to talk a bit about what Harpoon V helps explain and what it doesn’t.

Given that Moskva is a major combatant with a wide assortment of radars and defensive systems, the result of the attack/accident seems almost implausible. On paper this is a Ukrainian David vs. a Russian Goliath. Alternatively, how could the Russian Navy lose a ship to a fire? A closer examination of a plausible “engagement” using the Harpoon V rules reveals it’s not as lopsided as one might think.

Combatants

If reports are to be believed, Moskva was struck by by two RK-360MC Neptun (Neptune) anti-ship cruise missiles. Neptune is generally reported to be a Ukrainian version of the Russian Kh-35U but with a longer body, more fuel, and a larger booster. For the purposes of this discussion, let’s use the Kh-35U which is listed as the Uran (3M24) [SS-N-25 Switchblade] in Annex D1 of Russia’s Navy: Soviet & Russian Naval Vessels, 1955-2020 (Admiralty Trilogy Group, 2021). The most important data element is perhaps the damage caused by the 150kg warhead which Harpoon V rates as “35+D6/2” or 36-38 damage points. Admittedly, this number may be a bit low given the Neptune has more fuel and is larger, factors which lead to more damage in Admiralty Trilogy models.

Moskva is (was?) the lead ship of the Project 1164 Atlant class. To Cold War Grognards like me it’s perhaps better known as a Slava-class guided missile cruiser. The lead ship, Slava, entered service in 1983 and eventually was renamed Moskva in 1995. This particular ship was overhauled between 1991-2000 and was to be overhauled again in 2016. Reports indicate the overhaul stalled for lack of funds and the ship reentered service in 2019 with few—or none—of the planned upgrades completed. Full details for Moskva are found in Annex A of Russia’s Navy. Of particular concern to this analysis, Moskva is rated at 341 damage points.

The “Engagement”

There are many unanswered questions about how the Ukrainians may have hit Moskva with two ASCMs. In Harpoon V one can play out the detection, engagement, and damage results. While many pundits are saying that Moskva “should” have seen—and defeated—the inbound missiles, Harpoon V helps us understand why this may have not been an “automatic” thing.

Detection

• Missile Size/Height of Flight: The Neptune is a “Very Small” missile that approaches at “Very Low” altitude (Annex D)
• Radar Detection Range: The MR-710 Fregat-M (Top Steer) air search radar has a detection range of 27 nm versus a VSmall target (Annex J1)
• “A radar’s range is reduced by rising sea states, rain, and nearby land masses” (5.2.9 Environmental Effects on Radar)
  • Although it is unclear exactly where Moskva was operating, general weather reports from the region indicate poor weather with possible precipitation; assuming Sea State 3 with Light Rain the detection range is reduced by 40%
  • The Fregat-M is a 4th Generation radar so technically it should be able to deal with the environmental clutter and keep the full detection range—if the crew was properly trained.
• Missile Speed: The 3M24 flies at 580 knots, or almost 10 nm a minute. That’s a little less than one Tactical Turn (3 minutes, or 6x 30 second increments) in Harpoon V.

Once the missile was detected the ship’s defenses should have engaged. Maybe…but not so fast…

Of SAMs and CIWS…

• Reaction Time: Rule 8.1.1.3 covers Reaction Time; with a 3rd Generation SAM the normal delay is 3 increments (90 seconds) with a variable 0 to +4 increments added (see Combat System Reaction Time and Combat System Reaction on page 8-4).
  • Moskva at best may have gotten one SAM volley off and then point defense CIWS—if they were fully alerted at General Quarters
• SAMs
  • The S-300 Fort (5V55R) [SA-N-6a Grumble] has a minimum range of 2.7nm (Annex D1)
  • The Osa-MA (9M33M2 [SA-N-4a Gecko] has a range of .5 to 6.5 nm (Annex D1)
  • Using 8.1.1 Radar-Guided Surface-to-Air Missiles (SAMs), step 7) Punch the Table, we look up SAM Intercept Table – VLow Altitude Targets and cross-reference Subsonic & Transonic with 3rd Generation (Fregat-M radar) and get”S-P” meaning there will be one chance to engage at Short Range and one chance for Point Defense (good guess above!)
  • If the S-300 Fort got off a two-SAM salvo, the Probability of Kill (Pk) is around 80%; the Osa-MA is a bit less with a Pk of ~75% for a two-SAM salvo
• CIWS
  • Moskva mounts two, twin AK-130 130mm/70 guns; given the short reaction times involved I’m going to rule they were very likely not able to get into action fast enough to engage the inbound missiles
  • Moskva also mounts six AK-630 30mm close-in-weapon systems (CIWS); assuming one pair is able to engage at Point Blank Range it has roughly a 76% chance of knocking down a missile.

The defensive model in Harpoon V assumes ships are at General Quarters with all sensors and weapons at the ready. General Quarters is also very hard to maintain with watertight doors secured and people constantly on edge. It is more likely that Moskva was operating in some lesser readiness condition. This of course means sensors and weapons may not have been ready (extending the Reaction Time) and watertight integrity/damage control teams may not have been set to immediately deal with damage.

Damage (Out of) Control

Regardless of the defenses, if stories are to believed at least two ASCM got through and hit. Let’s see how Harpoon V portrays that:

• Applying Damage (14.1): Two hits cause ~74 points of damage which is less than the 85 needed to reach 25% damage and no loss in speed (14.1.1); 341-74=267 damage points remaining
• Ship Critical Hits (14.1.2): To compute damage ratio take 74/267 for a result of .277 rounded down to .2; the Critical Hit Damage Ratios table indicates a a D6 roll of 4 is 1x Critical, 5 is 2x Critical, and 6 is 3x Critical.
• Missile Impacts (14.1.5): Guided missiles cause additional Critical Hits because of the airframe and fuel based on the damage points from the missile; the 3M24 will cause D6/2 extra Critical Hits PLUS one Automatic Fire Critical hit
• Critical Hit summary: So far that’s between 0-6 Critical Hits with an additional automatic Fire Critical
• Fire Critical (14.4): Rolling D6 gets 3 or 3% of the original 341 damage points or 10 more damage points scored immediately (257 remaining)
• Flooding Critical (14.4): Let’s assume for the moment that one of those other Critical Hits was a flooding scoring 4% (13 DP) for a total of 97 hits or 244 remaining; this is more than 25% overall damage so speed is reduced
• Weapon Critical Hit/Mount Detonation (14.5): There are some reports that “broadside ammunition” was the cause of the fire. Moskva has those huge tubes for the P-500 Bazalt (4M80) [SS-N-12 Mod 1 Sandbox] missiles; if there was a Weapons Critical Hit that scored against this weapon, there is a 10% chance of detonation which would score 71+D6 damage (average 75?) reducing the damage points to 244-75=169 which is just under 50% remaining which means speed is reduced to 16 kts and kicking off another round of Critical Hits (75/169=.44 rounded to .4 for between 0-5 more Critical Hits)—it’s easy to see a snowballing damage effect here especially if more fires or flooding in involved…
• Fire & Flooding Severity Level (see 14.4): If Moskva suffered at least 16% in Fire and Flooding damage the crew is considered “Overwhelmed.” The damage is considered a “Conflagration” which has a 25% chance every Intermediate Turn (30 minutes) of causing a magazine explosion which can only be avoided by flooding the magazines and pushing ordnance overboard.

So why is everybody seemingly surprised at the outcome of events?

“Naval combat at sea has always been highly lethal to the participants.”

Captain Wayne P. Hughes Jr., USN (Ret.)

Unexpected Lethality?

The late Captain Wayne P. Hughes Jr., USN (Ret.) in his book Fleet Tactics and Coastal Combat Second Edition (Annapolis: Naval Institute Press, 2000) shared a study showing the number of Exocet equivalents (approximately equal to one 3M24) it would take to cripple or sink a warship (see Fig. 6-1, Exocet Missile Equivalents versus Full-Load Displacement for Ships Out of Action and Sunk, p. 160). The table goes up to 7,000 tons but extrapolating the data to ~10,000 tons (Moskva is 9,380 tons standard displacement) indicates that two hits are very likely enough to put Moskva out of action and four or five hits would be sufficient to sink the ship. Assuming two missiles and maybe one sympathetic detonation of ordnance that’s already three hits…with maybe a fourth from fire and flood damage. In many ways the surprise should not be Moskva sinking but if the ship somehow survives.

To be or not TB2

Part of the story of the Moskva attack includes the Ukrainians using a Bayraktar TB2 drone (Harpoon V stats found in The Naval SITREP #56) to “distract” the crew. Personally, I am unsure as to the chances that the Ukraine Navy would operate a TB2 at range (the datalink is rated in Harpoon V as 150 km range), at night, and in bad weather but it’s possible? Some allege the TB2 pulled off Moskva’s radars so they didn’t “see”the attack coming on on the other side. Note that the air search radars used aboard Moskva provide 360 degree coverage. A more plausible explanation to me is that the crew became fixated and focused on a potential TB2 threat and in turn failed (at night and in sea clutter) to see inbound sea-skimming missiles. This is a reality of life in combat and not necessarily replicated in a wargame simulation model.

Which is the real point of this post; wargames can help us understand more about a battle but in the end it cannot capture many human factors. Was Moskva ready for an attack? If not, how long does it take the crew to react (this is a major training issue). Was the crew “distracted” by a TB2 and lacked the discipline to maintain their sector watch and “missed” the inbound missiles? We may never know these answers.

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