Stan Brock is like a 21st-Century Florence Nightingale.
Originally it was to help poor tribes in the former British colony of Guyana, South America.
That is where he lived after leaving Preston, Lancashire, more than half a century ago - he still is a British citizen.
But now Stan spends most of his time bringing relief to the richest country in the world.
Some 60% of RAM's work is now carried out in the United States.
On a wet, spring weekend he lands his vintage World War II aircraft - once used to drop American troops on D-Day - in Lafayette, Tennessee.
He bought the plane to parachute medics into the jungle.
Today he is unloading dentists' chairs from the plane into a pickup truck.
By eight o'clock on Friday evening the first patients have arrived after travelling hundreds of miles.
They start queuing.
For one weekend RAM has turned a high school into a hospital.
Classrooms have become consulting rooms and the sports hall has been transformed into a production line to fill or extract painful teeth.
Volunteer nurses, doctors and dentists have flown in from all over the country to man the stations.Inside a 'free' health clinic in the USLike Stan, they are not getting paid.By five o'clock on Saturday morning the line is snaking round the school.State troopers are on standby to help.
The patients are handed numbers as they wait in the pouring rain.
Most of those I speak to seem to have jobs, but cannot afford healthcare.
For one reason or another they do not have insurance.
They call themselves the "working poor".
And then Stan Brock arrives with a loudspeaker to call the first batch in.
Once inside there is more queuing and waiting.
The patients slowly make their way to tables with yet more volunteers, who take blood pressure and medical history.
Among the sea of faces is Donna Pollard.
She wants a mammogram to check out a lump on her breast, as well as dental work and new eye glasses.
For her, this service is nothing short of a lifeline.
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Healthcare is a luxury when you are struggling to pay the bills.
Then there is Ken Barbee.
At 64, he has been working for most of his life.
But recently he had to give up his job as a truck driver to look after his sick wife.
By the time I catch up with him he has already got his new glasses - now he hopes to have his last few teeth removed.
Ken calls it "a shame" that people have to resort to charity for their healthcare in the world's most prosperous country.
He feels let down: "We're just pushed out there and told to do the best y'can."
And this is just the tip of the iceberg.
Some 47 million Americans have no health insurance.
Millions more are under-insured.
It is no wonder that healthcare is now such a big issue in the presidential race.
For a stoical Stan Brock, organising these clinics is both rewarding and depressing.
Come Sunday when it is time to pack up, he will be turning people away.
He watches over the whole operation wearing a neatly pressed khaki uniform, carrying a clipboard and pen, looking like a figure from the old British empire.
He has given his life to all this.
He takes no salary, and lives in an old school building in Kentucky from where he plans RAM's expeditions.
As for his views on America's healthcare, Stan says:
"We need to fix it... fall into line with Britain and France.
"Here in this country if you're poor - you don't have much of a shot."
In this one short weekend, RAM treated 550 people - 416 teeth were extracted, more than 200 pairs of glasses handed out.
The estimated value of this free treatment was nearly $1m (£500,000).
So Stan Brock will continue flying in healthcare to rural Appalachia as well as the developing world.
He is also seriously thinking of returning to Britain - with a team of RAM volunteers.
He has heard his old country has a shortage of NHS dentists.
"I am sure we'll get just as large a crowd as we're getting here in the US," he says.
© 2008 BBC News