Niall qualified as a doctor from Trinity College, Dublin in 1993. He trained as a surgeon in Belfast and received his FRCSI in 1997 before returning to Dublin where he worked in the National Cardiac Surgery Unit. He subsequently retrained as an airline pilot with Aer Lingus in 1999 and combined aviation with medicine by working as an Accident & Emergency doctor for six years before focusing fully on aviation. After operating as a co-pilot on both the European and Trans-Atlantic fleets, he qualified as a captain in 2010 and is currently operating out of their Belfast base on the A320 fleet. In 2011, he formed Frameworkhealth Ltd, a company providing aviation safety training modified specifically for healthcare which draws on his twenty-five years of experience between both industries.