He later returned to military service during the First World War, initially serving as a lieutenant in the Essex Regiment, before transferring to the Manchester Regiment. He was promoted to captain in November 1916, with seniority antedated to October of the same year. Airy was temporarily promoted to major in December 1917, while in March of the following year he was appointed an acting lieutenant colonel while commanding a battalion. Serving throughout the war, he saw action in Egypt and Gallipoli, in addition to the Western Front. Following the war, he was briefly seconded from the Manchester Regiment in April 1919. He returned to the regiment in October 1919 and was posted to Ireland during the Irish War of Independence, where he commanded 50 men at Ballincollig. He journeyed north to Macroom, where it was alleged on 17 July 1920 that he had assaulted a schoolgirl on her way home from school. Enraged by this, the Fermoy IRA sought revenge. On 18 July, they set up an ambush at Coolavokig, situated along the road between Ballyvourney and Macroom, where they laid in wait for three days. Airy was travelling as a passenger on board a rations lorry on 21 July, when it was ambushed by thirty IRA men that had laid in wait for him. He was fatally shot in the abdomen and succumbed to his wounds later that evening, alongside a Private Barlow.