The reason it is FDNY (Fire Department of the City of New York) and not NYFD (New York Fire Department) is rooted in history and the official name given by the Tweed Charter during the consolidation of New York City. The official name is "Fire Department of the City of New York," hence the acronym FDNY. This contrasts with the more common naming convention where the city's name precedes the department name. The FDNY name dates back to 1865 when the paid fire department replaced the volunteer fire departments, and when the Greater City of New York was consolidated in 1898, combining various fire departments into one organization under the FDNY name. This differentiation also helped distinguish it from the previously existing NYFD and avoid confusion with other departments like the NYPD, especially because NYFD and NYPD could look visually similar. In short, FDNY reflects the full historical and formal name "Fire Department of the City of New York," not just "New York Fire Department," and it has been maintained for historical and practical reasons.