HMS Queen Elizabeth has set sail from Portsmouth to head to the US in place of its sister ship.
The carrier is standing in for HMS Prince of Wales, which broke down off the Isle of Wight at the end of August.
The warship had been on its way to the coast of North America for three months training, including flight trials with F-35B Lightning stealth fighter jets.
HMS Queen Elizabeth's crew were notified earlier this month that they would be sailing to the US instead.
Families of crew members and well-wishers lined the walls of Portsmouth Harbour on Wednesday morning and waved union flags to see the carrier off.
The Navy has not detailed which of HMS Prince of Wales' diplomatic engagements and military exercises will be carried out by HMS Queen Elizabeth.
The programme included the Atlantic Future Forum and port stops in New York, Canada, and the Caribbean.
HMS Prince of Wales went back to Portsmouth Naval Base on Saturday after a coupling on its starboard propeller shaft broke.
The £3bn aircraft carrier will need to undergo repairs, which could be carried out at Rosyth in Scotland.
Follow BBC South on Facebook, Twitter, or Instagram. Send your story ideas to email@example.com.
Fleet flagship likely to take on US training trip
Warship may miss US jet trials after breakdown
Royal Navy carrier breaks down off south coast
Queen Elizabeth II has died
UK and world react to death of the Queen
Notice of death of Queen Elizabeth II, Holyroodhouse. Video
The British-era colonel revered in India state
The meteoric rise and dramatic fall of Boris Johnson
The British isles that disappear every day
'There's more to life than achieving a KPI'
© 2022 BBC. The BBC is not responsible for the content of external sites. Read about our approach to external linking.
Surviving The 2nd Wave of Corona
‘This too shall pass away’ this famous Persian adage seems to be defeating us again and again in the case of COVID-19. Despite every effort