Sir Cliff Richard burst into a rendition of his hit Summer Holiday on board a Florida-bound plane carrying 192 seriously ill or disabled children on Sunday afternoon.
The veteran pop star serenaded the excited group before the plane took off from Heathrow on the holiday of a lifetime thanks to British Airways-supported charity Dreamflight, writes the Press Association.
Now in its 27th year, Sir Cliff said the annual trip - which includes the opportunity for each child to swim with dolphins - is "probably one of the most exciting things that's happened" in the children's lives.
Having just jetted in from Miami to wave goodbye to the group, who are from all over the UK, he said: "Dreamflight is such a wonderful idea. The fact that these very sick children who have a dream of going to Disney, and suddenly, there's this plane.
"They have the most fantastic time.
"It's probably one of the most exciting things that's happened to them in their lives."
The children have left their families behind and will be looked after during the action-packed week of fun by 15 doctors, 50 nurses and 12 or 13 physios - all volunteers.
Sir Cliff described the work of Dreamflight as "vital" and said it makes him feel positive about the world.
"All charity is vital. How do these people have a life? How do they get something as magical as this without a charity involved?
"It warms my heart, because it goes to show that with all the evil there is in the world, there are obviously people who will give their time, give their money, give their commitment and dedication to help young sick children have maybe one fabulous moment in their lives.
"I think it's worth every penny that it costs."
Sir Cliff, who has been involved in the charity for 20 years, sang Summer Holiday through the plane's PA system before it pushed back and took to the skies.
To fit in with the occasion, he changed the lyrics to Dreamflight Holiday, adding: "No more sickness for a week or two."
A crowd of airport staff waved the children off and fire engines soaked the plane in a water canon salute as it approached the runway.
Sisters Georgia and Lottie Conley, 13 and 11, from Bedford, said they were so excited they were "jumping around all day".
Charity sends dad with brain tumour to Disneyland Paris as final wish
151 Santas go diving in Somerset