PL Ferrari has warned that ship masters should only switch off the AIS for “legitimate” reasons.

The protection and indemnity insurance broker's note to clients came after the US Department of the Treasury's Office of Foreign Assets Control (OFAC) last month stepped up its surveillance of ships trading around Iran and North Korea.

OFAC has identified suspension of AIS signals as a key indicator of sanctions-busting ships.

Security measure

But “going dark”, as it is known, is also commonly used as a security measure by ships to guard against threats such as piracy off the East Coast of Africa.

Vessels can also fail to transmit their position due to a breakdown or transmission black spots.

Ferrari said in its note to owners that masters need to document the reasons for not using AIS.

“We know there are legitimate reasons to switch off or switch to a low-power AIS signal," the broker said. "However, it is of extreme importance that the master, for whatever the reason, keeps a clear record in the records or logbooks noting the context and reason for doing so as evidence to the various interested authorities.”

The concern is ships that switch off AIS for legitimate reasons could be tagged as sanctions busters by the US authorities. P&I club Gard told its members: “Going dark in areas of heightened surveillance is a red flag to authorities.”

Ship data analysis company Windward has identified a total of 14 tankers operating in the Persian Gulf that have displayed suspicious behavioural patterns.

This included “going dark”, which raised suspicions that ships were involved in sanctions-busting activities.

Recent advisories by OFAC mean it is incumbent on all parties in the maritime supply-chain to screen vessels for deceptive shipping practices, such as AIS manipulation


The analysis included the 300,000-dwt VLCC Pacific Bravo (built 2001), owned by the Chinese Bank of Kunlun, which switched off its AIS for five days while operating near Iran’s Kharg Island Oil Terminal.

Busting sanctions

The vessel has been identified by the US as being under suspicion of breaking US sanctions on Iran.

Windward said responsibility for identifying sanctions-busting vessels runs through the shipping industry.

“Recent advisories by OFAC mean it is incumbent on all parties in the maritime supply-chain to screen vessels for deceptive shipping practices, such as AIS manipulation,” Windward said.

The other issue around switching off AIS is that it could potentially remove P&I cover from vessels.

The continued use of AIS is a requirement of the International Convention for the Safety of Life at Sea and vessels that are not using AIS, without legitimate safety or security reasons, would be in breach of flag-state requirements.

“Where a ship is not in compliance with flag-state requirements, there may also be grounds to withdraw P&I cover on the basis of imprudent or unlawful trading and/or disguising the ship’s location by manipulating or withholding the transmission of AIS data,” Ferrari said in its note to owners.

The 300,000-dwt VLCC Pacific Bravo (built 2001), pictured under its former name of Kumanogawa Photo:

Removing cover

As TradeWinds reported previously, P&I clubs are also being encouraged by OFAC to remove cover from vessels that switched off AIS signals while trading near countries under sanctions.

The clubs have demonstrated a willingness to operate in full compliance with US and European Union sanctions. However, there is a resistance among P&I clubs to being forced to police the compliance of individual members' ships on behalf of the US authorities.