Robert Bertelsen served as a pilot first with the 564th Bomb Squadron of the 446th Bomb Group, then from April 1944 with the 566th Bomb Squadron of the 389th Bomb Group. He transferred to the 2nd Scouting Force and was killed due to engine failure in AT-6 43-13984 on 11 September 1944. He is buried in Golden Gate National Cemetery, California.

Bertelsen was inducted into the Army Air Corps just three weeks before Pearl Harbor and was to complete his Aviation Cadet Training at Lubbock, Texas in June of 1943. In October he linked up with the 446th BG in Nebraska and shipped out with them to their base in England.

His missions from Bungay included one in Februarys 1944 on the ME 110 factory in Gotha when his plane 'The Beast' dropped out of formation due to technical problems and went on to bomb a 'target of opportunity'. The next available record is of him flying in the pathfinder role in the run up to D-Day. Later that month he was apparently re-assigned to the pathfinder 389th BG with whom he completed his original tour.

The records show that he was then - probably in August 1944 - offered a job with the 355th Fighter Group whose speciality was scouting ahead of the bomber stream. It was thought that pilots with bomber experience were best suited to that role. The pilots were re-trained on the AT-6D before progressing on to the P-51 Mustang. It is documented that five of these ex-bomber pilots lost their lives in this transition. Amongst them was Robert Bertelsen who died on the evening of September 11th 1944 in an AT-6D (43-13984). He crashed near the field at Steeple Morden, cause of accident 'undetermined'.