This new, six-part observational documentary series is filmed onboard the aircraft carrier HMS Illustrious during a four-month deployment. The programme follows the professional lives of the crew as well as the personal stories of the young men and women who are thousands of miles from home. In the first episode, problems plague Illustrious’s departure from Portsmouth and the crew members are assessed to see if they are battle-ready.

The mighty Illustrious aircraft carrier is about to set sail on a four-month deployment. With a crew of 1,000, this 22,000-ton floating city – nicknamed ‘Lusty’ – is home to all manner of sailors, from stewards to engineers, officers to deckhands. The ship’s projected route will take it through the Strait of Gibraltar, across the Mediterranean and through the Suez Canal to the Indian Ocean, where it will support Harrier jump jets serving in Afghanistan.

The man overseeing this massive operation – two years in the planning – is Captain Steve Chick, on his first mission in charge of an aircraft carrier. “Obviously, there’s an element of nervousness for anybody in taking command of a ship for the first time,” he says. “Getting to know the ship, getting to know how it handles, getting to know the people.”

Captain Chick’s crew includes a large number of new recruits, each of whom has his or her own reason for signing up. Lieutenant John ‘Sid’ Little left a job in a clothes shop to serve as a trainee weapons engineer. “It wasn’t really what I wanted to do for the rest of my life, so I thought I’d make a career choice and join the navy,” he says. Trainee warfare officer Suzie Williford sees the navy as her calling. “I realised this is what I wanted to do,” she says. “I wanted to drive ships. I wanted to be in command.” Nineteen-year-old John Farnsworth, meanwhile, was attracted by the prospect of playing for the ship’s football team.

Lusty herself is older than many of her crew, having been commissioned in 1982. The ship has been refitted several times to keep her in service beyond her original lifespan. “I think she’s a very elegant but very classical old lady,” says engineer Helen Ashford. However, wear and tear is beginning to take its toll, and this is immediately apparent when Lusty is forced to return to dock with a broken fridge two days after setting sail.

The incident makes for some uncomfortable headlines in the press, but the giant fridge must be repaired or the ship’s £25,000 store of food will be ruined. While in dock, a more serious problem develops with the engines, and the engineers have to work round the clock to fix them. By the time Illustrious gets underway, she is running five days behind schedule.

Once at sea, life can be tough for the crew, which includes 100 female sailors. They must put up with cramped quarters and strict regulations – including a ‘no touching’ rule to prevent fraternisation. “It’s human nature that relationships will happen onboard,” says trainee warfare officer Milly Harrandine. “When you’re at sea, you should keep that to yourself. You should act professional.”

Before Lusty can depart British waters, the crew members must pass tests to prove they are battle-ready. Tensions run high as a team of tough naval inspectors arrives onboard to stage a series of mock battles. Kitted out in fireproof suits, the sailors are put through their paces in everything from firing weapons and fighting fires to first aid and cooking meals under pressure. “You’ve got to get it right,” says inspector Captain Michael Cockran. “If you get it wrong, people get killed.”

Unfortunately for the Lusty’s eager but inexperienced sailors, they fail the first test. The ship docks in Portland, Devon and crew members are allowed 48 hours’ shore leave to let their hair down as only sailors know how. But when yet another problem strikes the engines, rumours circulate that Illustrious must return to Portsmouth for a two-month layoff. Is the trip over before it has even begun?