In the Canadian rank structure since about 1970 master corporal is a junior enlisted rank.
The enlisted Air Force ranks in order are:
Private, corporal, master corporal, sergeant, warrant officer, master warrant officer, chief warrant officer.
The commissioned ranks are:
2nd Lieutenant, Lieutenant, Captain, Major, Lieutenant Colonel, Colonel, Brigadier General, Major General, Lieutenant General, General.
There is also the position of Officer Cadet which is an officer in training who has not yet been awarded a King’s commission.
My thanks for your family’s service.