'Going dark': How first oil tanker to reach Mumbai since Iran war began navigated conflict-hit Strait of Hormuz

The tanker, Shenlong, captained by an Indian, has become first India-bound vessel to safely navigate the strategic route since

A Liberian-flagged ship bound for India, loaded with crude oil from the Saudi port of Ras Tanura, passed through the conflict-hit Strait of Hormuz after briefly 'going dark' to avoid detection and has arrived at the port of Mumbai.

The Suezmax tanker, Shenlong, captained by an Indian, has become first India-bound vessel to safely navigate the strategic route since the United States and Israel started air strikes on Iran and Tehran retaliated by targeting oil fields and refineries in Gulf Arab nations. Iran has stopped cargo traffic through the narrow Strait of Hormuz, through which a fifth of all traded oil passes.

The Mumbai-headed vessel departed from the Saudi port on March 1 and while navigating the conflict-hit strait, it went 'dark' — turned off its transponders and automatic identification system (AIS), to avoid detection, according to a Hindustan Times report. Its last signaled location before 'going dark' was inside the strait on March 8, according to maritime data firms Llyod’s List Intelligence and TankerTrackers. The vessel re-appeared on tracking databases on March 9.

The ship, carrying 1,35,335 tonnes of crude oil, reached Mumbai port on Wednesday. The crude oil will be supplied to refineries in Mahul in eastern Mumbai.

What is ASI?

The automatic identification system (AIS) in ships normally broadcasts its identity, location, course and speed to other ships and monitoring authorities. International Maritime Organization's regulations require the AIS to remain active at all times when vessels are underway or at anchor to enhance safety and tracking. However, in high-risk zones, including conflict situations, the AIS can be deactivated — 'go dark' — if the ship's master deems its continuous operation would jeopardize the vessel's safety or security, as per the regulations. While turning off the AIS reduces the risk of being targeted by adversaries, it increases the risk of collision and complicates search and rescue efforts.

Attack on vessel

On Wednesday, a Thai-flagged bulk carrier, Mayuree Naree, which was on its way to Kandla Port in India, was attacked by Iran's Islamic Revolutionary Guard Corps (IRGC) in the Strait of Hormuz. Two seafarers from India were killed, and another went missing following the attack.

Earlier, the commander of IRGC Naval Force had said that vessels seeking to sail through the Strait of Hormuz must obtain Iran's approval; otherwise, they could become targets of Iranian attacks. Rear Admiral Alireza Tangsiri had said that two ships that had ignored Iran's warnings were targeted in the strait on Wednesday.

"Were the ships assured of safe passage through the Strait of Hormuz? This should be asked of the crews of the vessels Express Rome and Mayuree Naree, who today, trusting in empty promises, ignored the warnings and intended to cross the strait, but were caught. Any vessel intending to pass must obtain permission from Iran," he said in a post on X.

28 Indian-flagged vessels

India's Shipping Ministry on Wednesday said that 28 Indian-flagged vessels are operating in the Persian Gulf region. Of these, 24 vessels are located west of the Strait of Hormuz carrying 677 Indian seafarers, while four vessels are east of the strait with 101 Indian seafarers onboard.