the award was established on 3 june 1918, shortly after the formation of the royal air force (raf). it was originally awarded to raf officers. during the second world war, it was also awarded to royal artillery officers serving with the raf as pilots and artillery observers. in 1993 the medal replaced the distinguished flying medal, which had until then been awarded to other ranks. people awarded the distinguished flying cross are allowed to use the post-nominal letters "dfc". a bar is added to the ribbon for holders of the dfc who received a second award.