A group of mountain bikers were going downhill in Whinlatter, Lake District, when one of them crashed and was knocked out.
The man, aged 42, was unconscious and his pals dialed 999.
A member of the Keswick Mountain Rescue team recognised the personal details given as likely to be his son - and rushed to get to the scene on January 29, just before 1.30pm.
An RAF mountain rescue team who were training in the area also attended, with ten rescuers at the scene.
The team vehicle was able to park close to the incident and on arrival the casualty had re-gained consciousness and was sitting up with a space blanket and warm clothes provided by his friends.
After a thorough check over by a team doctor the man was able to walk to the team vehicle and was driven down to an awaiting ambulance.
He was taken to the Cumberland Infirmary at Carlisle for further checks but was later discharged.
Although suffering from concussion he had chosen that day to use a full face helmet which saved him from more serious injuries.
His dad later said: “You never stop worrying about your kids – even when they’re 42."