RFA Argus has returned to sea following an extended refit in Cornwall.
The Primary Casualty Receiving Facility has started sea trials ahead of planned operational sea training in the spring.
The ship left Falmouth Docks to make its way back to sea.
"The purpose of the refit is really to put right a number of the defects that the ship’s suffered over her previous few years at sea," Captain Kevin Rimell told Forces News.
"Some modifications that needed to be done and it's generally just to get the ship ready to then start the next phase of her operational service."
The 40-year-old vessel has received a new paint job, work on her flight deck, with her main engines also being overhauled.
It is the first time the engines have been used at sea since 2018 and for Third Officer Tim Salvidge, it meant a late night at sea as the engineers gradually put the engines through their paces.
“The refit, in general, was massive," Third Officer Salvidge said.
"Loads of stuff was being done to the ship but the engines specifically have been completely stripped back, inspected.
"The other day we had to do a full piston and liner change as well."
“Running the main engines, running the steering gear, running the bow thrust, all of that kind of machinery that it isn’t used just to maintain the hotel services,” said Captain Rimell.
"All that’s being used for the first time and you don’t have the safety of the lines that are attaching you to the jetty.
"So all of that is being used for the first time.
"There’s always a risk it might not work."
Formerly a merchant vessel Argus' primary role is as a Primary Casualty Receiving Ship, and contains a 100-bed medical complex on board.
However, when her medical facilities are not required she is used to train less experienced pilots in deck landings.
"We’ve got quite a lot of new people, a lot of young ABs (Able Seamen) on board," said Lieutenant Amy Lewis-King.
"So it’s really important to get them up and running and comfortable in the role they’re going to be doing. So we’ll start off nice and slowly.
"Sort of the ‘crawl, walk, run’ as a phrase we that we like to use.
"But very much starting off with that one aircraft and as the tempo increases, very much lots and lots of flying going on."
It is hoped the first aircraft will land on board Argus in February, before joining large pre-planned exercises in the spring.