After service as a pilot during the First World War, McIntosh became a pioneer civilian aviator, flying primitive airliners from London to Paris, and back. On one occasion, as he approached London, thick fog blanketed the airfield. However, McIntosh observed that the radio mast at the airfield was protruding above the fog. Knowing the position of the radio mast relative to the runway, and timing each leg of the approach, in order to judge his distance covered "over the ground" McIntosh descended "blind" into the fog, and successfully landed the aircraft. Next morning a British newspaper ran the headline "A Macintosh for all weathers", refering to the Macintosh raincoat, and the nickname stuck. McIntosh went on to command an Air-Sea Rescue squadron during the Second World War, and flew on operations, despite being considered an elderly man, in his mid-40's.