According to a report by the Ukrainian news site Pravda, the operation relied on the random occurrence of an unusual weather phenomenon known as “ducting”. As a result, the coastal defense radars could see much further than usual, allowing the coastal defenders to launch a deadly missile attack. If true, and so far this seems likely, it helps explain how a country with virtually no navy managed to sink one of the largest surface warships in the world. Russia has not confirmed this option.

Through the eyes of Jiří VojáčekSource: DiaryIn the period before Russian invasion to Ukraine, the Russian Navy has assembled three of its largest ships, the Slava-class missile cruisers, in and around the Black Sea. She also belonged to them Moscow, the flagship of the Russian fleet in the Black Sea. Russia has assembled its warships to assert naval superiority and assist in an amphibious landing on Ukraine’s southern coast. The landing never actually took place and the assembled fleet gradually dispersed. Moscow remained in place and, according to Western estimates at the time, moved approximately one hundred kilometers from the coastal city of Odessa.

A hundred kilometers is not a long distance in modern naval warfare, but Moscow was virtually untouchable against the weak Ukrainian air and naval forces. Ukraine had only one large surface warship, the Hetman Sakhaydachnyi, and this frigate was sunk early in the war to avoid capture by advancing Russian forces. Meanwhile, all available Ukrainian air power was devoted to fighting the ground invasion.

It was known in professional circles that Ukraine has been working on a new anti-ship missile for the past few years Neptunebut little was known about whether this missile was operational, what principle it was based on, and how many might be available.

Russian cruiser Moskva before sinking.Source: CTK/XINHUA/Zhang Jiye

The sinking theory

There are several theories about the sinking of Moscow. One of them stated that the ship’s location was provided by a US Navy P-8 Poseidon aircraft, although The Pentagon denied, that he would provide Ukraine with “specific information about the location” of the ship. Another theory stated that TB-2 Bayraktar drones were tracking the Russian Black Sea flagship in the open ocean. This theory was supported by a later statement by Ukrainian officials, who stated that “other devices” also contributed to the sinking.

A few days old report by the Ukrainian daily Pravda suggests that Ukraine was telling the truth, that it was a simple radar targeting all along. The newspaper reports that the cruiser Moskva was actually located less than 120 kilometers from the Ukrainian coast, thus beyond the range of Neptune’s ground-based detection radars. Modern ground-based radars in recent decades are usually limited in detection length only by the curvature of the Earth, especially against targets that move low at sea level.

“Since there were thick clouds over the sea, the signal from the radar reflected from them to the water surface and from the water back to the clouds,” reports Pravda. As a result, the coastal defense radar suddenly saw further than usual and revealed a large radar reflection anchored off the coast. At that moment, the Ukrainian radar operators realized that they had detected Moscow, which they knew was somewhere in these places, and fired two Neptune missiles at it.

Both missiles hit the cruiser on the port side amidships, the subsequent fire then spread to the ammunition store, which exploded. The mortally wounded 186-meter-long cruiser still tried to reach the port, but could not make it and sank.

Is the new Ukrainian theory true?

The phenomenon used by the radar operators of the Neptun radar system is known as “ducting”. The U.S. National Weather Service describes this phenomenon as follows: “If the atmospheric conditions that cause superrefraction bend the beam by as much or more than the curvature of the Earth, a condition called ducting or trapping occurs. Ducting often leads to spurious echoes, also known as anomalous propagation.”

Christian Wolff, an independent radar engineer and author of radartutorial.eu, an expert website dealing with radar technologies, dealt with the issue. “We can only speculate as to how the exact position of Moscow could be detected by radar,” he says, “ships usually disappear over the horizon after about 40 nautical miles. A classic radar placed on a flat coast cannot detect them.

This is because the natural conditions for the channel effect depend on the air temperature. When layers of air have significant temperature differences, then the boundary between these layers can reflect electromagnetic waves. This creates a transmission channel for the radar, similar to an optical cable,” explains Wolff.

He also suggests another possible explanation that would not require clouds. “To achieve such a channel effect, very high air humidity up to a height of about 10 to 15 meters above sea level can also be used. This effect is more independent of the weather. However, for this, the radar would have to be located directly on the coast and work with high transmission power and an antenna with strong directivity.”

The sinking of the Moskva was a huge blow to the Kremlin, one of many during its invasion of Ukraine. It could rely on the bravery and skill of its own soldiers, and on the contrary, the incompetence of the Russian army. That is why it has held off the invasion until now, and now the occupying troops are gradually pushing back.

With the defenders of Ukraine, it is no longer just the world community, courage and luck wishing the prepared, but, it seems, nature as well.