On 30 July, she sailed for Durban to begin a refit that lasted from 15 August to 10 October and arrived back at Trincomalee on 1 November. 810 Squadron and its Barracudas were transferred off the ship the next day and were later replaced by the Avengers of 854 Squadron. For the next six weeks she carried out an intensive flying regime in preparation for the next operations against the Japanese together with the other carriers of the fleet. On 22 November she was assigned to the newly formed British Pacific Fleet (BPF), commanded by Admiral Sir Bruce Fraser. She was assigned to the 1st Aircraft Carrier Squadron (1st ACS), commanded by Rear Admiral Sir Philip Vian when he arrived at Colombo aboard the carrier . A week later, "Illustrious" and "Indomitable" sortied to attack an oil refinery at Pangkalan Brandan, Sumatra (Operation Outflank); the former's airgroup now consisted of 36 Corsairs of 1830 and 1833 Squadrons and 21 Avengers of 857 Squadron. When the aircraft approached the target on the morning of 20 December, it was obscured by clouds so they diverted to the secondary target of the port at Belawan Deli. It was partially obscured by clouds and heavy squalls so the attacking aircraft had only moderate success, setting some structures on fire and destroying several aircraft on the ground.