Prior to enlisting in World War 2 Allan Ritchie found work as an accountant. He was married to a woman by the name of Beth Ritchie and together the two of them made a home for themselves in Roseville, NSW.

Allan would find himself joining the Royal Australian Airforce on the 30th of January, 1943. He was selected from the start to train as air crew and for the first several months he was rated as being "Good" in his abilities with a "Very Good" character. He steadily rose through the noncommissioned ranks as he progressed through his training, and on the 11th of November was awarded his Air Gunner brevet having trained as a wireless operator holding the rank of Warrant officer.

It wasn't long after this that Ritchie embarked from Australia on the 26th of November. Upon arriving in the UK, he undertook further training with a primary focus of bomber aircraft, flying in such planes as Anson's, Wellingtons, Halifax and Lancaster's. In total this further training landed him a total of 182-190 hours of flying time in bombers. After completing this training Allan moved to No.460 Squadron RAAF in early November 1944. Between that time and May 1945 Ritchie would fly a total of 27 sorties with No.460 squadron in a total of 160-200 hours spent in the air. Approximately 20 of these were bombing missions, 3 trips to Rotterdam as part of the supplies and relief operations for Dutch civilians (The missions took place on the 3rd, 4th and 7th of May 1945) and 2 exodus trips to bring back a total of 48 POWs (These taking places on the 10th and 11th of May 1945). Out of all these missions, 16 of them were flown aboard the Arvo Lancaster bomber AR/L PB285. that plane would fly a total of 128 missions throughout the war.