Eighteen lives have been saved as a result of air ambulances carrying blood on board, the charity has said.
The Great North Air Ambulance Service (GNAAS), which covers the North East, Cumbria and North Yorkshire, started the scheme in January 2015.
Since then, medics have performed 60 transfusions, a third of which were deemed to have been of critical importance to survival.
Many others have had their outcomes improved by having the intervention.
Dr Rachel Hawes, who is also a doctor on the air ambulance, used her experiences as officer in the Army Reserve –