Allan Mclean, 72, became ill suddenly on a First Aberdeen service on February 3. The driver, Shane Mitchell, pulled over and performed CPR until paramedics arrived. Mr Mitchell, who has been with the company for more than two years, was later told his actions had saved Mr Mclean's life.
Mr Mclean, a retired labourer, said he would forever be indebted to Mr Mitchell, adding: "There is no doubt in my mind he saved my life. I am incredibly grateful I am able to continue enjoying my life and spending time with my two children, my grandson and my two granddaughters."
Mr Mitchell, who has been given an award for his action by his employers, said: "I knew something was wrong because the gentleman's lips had turned blue. I opened his shirt, checked his airways and then began CPR.
"I just kept going until the ambulance arrived, hoping I could get some form of response.
"I just did what anyone would have done in those circumstances."