As a squadron they flew their 12 Avengers to the west coast of the United States and embarked on HMS Shah at Alameda in January 1944, where a Grumman Wildcat fighter flight was added.

They sailed to the Indian Ocean via Williamstown docks, Australia to Cochin, where the carrier's deck cargo of aircraft was unloaded, thus enabling 851 Squadron's naval flying operations for the first time.

Tasked with anti-submarine patrols in the Indian Ocean and Bay of Bengal, 851 Squadron's Avengers and Wildcat flights briefly operated from a shore base at Colombo Racecourse, then at Katukurunda, as well as forming the Shah's full complement.

The aircraft directed the RN frigate HMS Findhorn and the Indian sloop HMIS Godavari to the submarine and they were able to sink U-198 with the loss of all hands.

This was the longest range Fleet Air Arm round-trip carrier borne attack of the Second World War.