Iranian ‘ghost ships’: Cock-up or conspiracy?

Tankers in the Strait of Hormuz. Credit: Getty Images
Tankers in the Strait of Hormuz. Credit: Getty Images

The media has been awash with stories of National Iranian Tanker Company (NITC) vessels turning off their transponders in local waters and then reappearing, as if by magic, en route to India or China, laden with several million barrels of oil. Accused of clandestinely loading and exporting crude, false draught reports, and secret ship-to-ship transfers, the case seems open and shut. Yet there is debate over how prevalent these activities are.

IHS Markit monitoring of NITC vessel movements from 2012 to 2016 shows that while they occasionally switched off their AIS vessel tracking system during long-term floating storage, it went little further than that. “The rumours and stories that they were regularly switching off AIS appeared at best to be the product of a poor understanding of the capabilities of AIS tracking using terrestrial and satellite based receivers, and at worst a deliberate misinterpretation of the situation to suit individual agendas,” one researcher told IHS Markit.

The AIS system is designed to communicate data between ships in visual sight of each other, only being able to function beyond about 45 km because of an atmospheric phenomenon called tropospheric ducting. Satellite-based AIS tracking is swamped in areas of high traffic such as the Gulf, while a lack of receivers on the Iranian coast leaves Arab countries reliant upon tropospheric ducting to maintain coverage in the north of the Gulf. High temperatures allow this to happen easily in summer, but coverage drops off rapidly as the area cools in the autumn. The vessels are still transmitting, but undetected.

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“This drop-off is often seized upon as evidence that the Iranians are switching off their transmitters, which is of course a false interpretation,” the researcher noted. That said, this does not mean that NITC vessels cannot be turning their transponders off, and the evidence is mounting.

“There has been a substantial increase in clandestine behavior in August and September,” IHS Markit research analyst Edward Moe told IHS Markit, citing a step-change in the number of vessels moving for days without any AIS signal being received. Vessels have been seen to arrive nearby the Strait of Hormuz and disappear – whether through deliberately sailing into an AIS-free zone or turning off their transponders – and then reappear several days later fully laden, in a timeframe that would not have allowed them to reach Kharg Island, before sailing all the way to China.

“I don’t have the satellite coverage to confirm that that there was a ship-to-ship transfer, but that does seem the most likely explanation,” Moe said. Clandestine loadings such as this accounted for an estimated 12 million barrels of crude in the first three weeks of October alone, against 8 million barrels captured by the standard reporting system, Moe explained, adding, “These [clandestine] movements seem to occur in ways that are remarkably convenient if you were trying to hide exports.”