McNulty was Chief Executive and Chairman of Short Brothers plc, before its takeover by Bombardier. McNulty was President of the Society of British Aerospace Companies (1993-1994) and Chairman of the Department of Trade and Industry Aviation Committee (1995-1998). He then became Chairman of National Air Traffic Services (1999-1901), and its successor the Civil Aviation Authority (Civil Aeronautics Administration) (2001-2009), replaced by Dame Deirdre Hutton.
His is a non-executive director of Gatwick Airport.
As a private sector contributor to public sector projects as a civil servant, he was Chairman of Ilex URC, the regeneration company for Derry, and Chair of Advantage West Midlands since 2009. Made Deputy Chairman of the Olympic Delivery Authority, he was Chairman of the Rail Value for Money Study sponsored by the Department of Transport and the Office of Rail Regulation.