The society will pay the charity a bonus each year, depending on total balances, and it could eventually be worth more than £50,000 a year.
Yorkshire Air Ambulance flies about 1,000 missions a year and needs £1.5 million a year to operate.
It has one helicopter, based at Leeds/Bradford airport, which carries a pilot and two paramedics.
Wherever it lands a hospital is within 10 minutes flight.
A Barnsley Building Society spokeswoman said: “We have agreed to pay Yorkshire Air Ambulance the equivalent of one per cent of the average daily balances held within the account each March, to coincide with the launch date.
Charlotte Leighton, aged 11, from Easingwold, York, was the first to open an account.
Charlotte was involved in a horrific car crash, that left her with terrible injuries including a partially severed tongue and lip and a fractured jaw and eye socket.
She could barely smile and was expected to suffer complications from conventional surgery, which would have involved a titanium plate and screws and numerous operations.
Instead, a surgical team used a sonic welding kit, flown in from Germany, to perform the first procedure of its kind in Britain. Three weeks later Charlotte was back home in York.
She returned to Leeds General Infirmary, a year after the accident, to thank the surgeons who rebuilt her face and hand over a sonic welding kit worth £7,500, donated by the suppliers, Albert Waeschle. Richard Loukota, a consultant facial surgeon, said: “Charlotte’s fantastic recovery is proof that this new technology can radically improve outcomes for children with severe facial fractures. The team here is absolutely thrilled. The sonic welding kit will enable us to offer the very latest in facial surgery.”
The operation, three weeks after Charlotte’s accident, was the first time in the world that sonic welding had been used on a lower jaw. It took 2½ hours, less than half the time of conventional surgery.
The use of metal or titanium can lead to complications in children because their bones are still growing and plates can move, which then leaves the patient requiring further surgery.
But sonic welding uses reconstructive plates and screws made of polylactide, a biode-gradable material that is broken down by the body over time.
“This new technique is easier for surgeons to use and has significant benefits for the patient in terms of shorter operating times and fewer postoperative complications,” Mr Loukota said.
“When Charlotte came to us she was gravely ill. The team and I are extremely pleased with the way the surgery went and are delighted she has made such a good recovery. Charlotte will be reviewed regularly over the coming months but all the signs so far are very encouraging.”
Charlotte was knocked down by a car on her way to school last summer, suffering fractures and cuts to her face, broken teeth and a severely broken leg. The skin was ripped from her nose and parts of her head.
Her parents were warned that she might not survive. Charlotte’s mother, Sue Leighton, said: “She’s fantastic, to look at her you would never believe what she’s been through.
“I’m so proud of her, she’s never complained, she’s definitely taken it all in her stride. “Now she’s got a couple of little scars on her face. If she had had the metal plates put in she would have had to undergo more surgery. Hopefully, now she won’t.
“She used to be a very quiet little girl before the accident. Being in hospital for so long she had to tell them all how she felt. Now she tends to speak her mind.”
Three more British hospitals have taken delivery of the new equipment since Charlotte’s accident.
Charlotte's dream was to be a cheerleader, so the Wakefield Wildcats arranged for her to take part in Swing with Ray last week, where she learnt a specially choreographed routine, which she performed alongside X-Factor star Ray Quinn when he provided the pre-match entertainment for the Wildcats v Bulls clash on Easter Monday. Charlotte then got to meet Ray.
