North Queenslanders came in as the top contributors among regional Queenslanders with more than 20,000 customers contributing regularly.

Ergon's chief executive Ian McLeod paid tribute to "a remarkable demonstration of community spirit towards a very vital and worthy cause."

"Even though many of our customers have been doing it tough, it has only taken about 12 months for their total donations to jump from $5 million to $6 million - that's inspiring," Mr McLeod said.

Through the scheme customers can contribute regular donations through their quarterly bill, or make larger one-off donations if they wish.

Since the project launched in 2000, more than 100,000 customers have chosen to make regular contributions.

Ergon staff have also contributed to RFDS through payroll deductions, with around $10,000 donated in this financial year alone, Mr McLeod said.

"We're all very proud to continue to support the great work of the RFDS."

RFDS Queensland Section CEO Nino Di Marco said donations raised through the Ergon Energy scheme were vital to keeping the Flying Doctor flying.

"We know many Ergon customers were affected by the recent flood crisis, and we saw the effect of those floods on rural communities as we evacuated patients from hospitals and nursing homes out of harm's way," Mr Di Marco said.

"It really is very heart warming that people in these hard hit areas have continued to support the RFDS through this scheme.

RFDS senior medical officer Don Bowley said Ergon's contribution was a tremendous support to Mount Isa's flying doctor service.

"For over 10 years, Ergon Energy, staff and customers have played an important part in helping the RFDS provide health care services to the people of Queensland, 24 hours a day, 365 days a year," he said.

"Reaching the $6 million milestone is an enormous achievement, helping us to purchase life-saving aircraft and vital medical equipment."