Greenwood Lake Airport (FAA LID: 4N1) is a public use airport located one nautical mile (2 km) east of the central business district of West Milford, in Passaic County, New Jersey, United States. The airport is owned by New Jersey Department of Transportation. It is included in the National Plan of Integrated Airport Systems for 2011–2015, which categorized it as a general aviation facility. An old Lockheed Constellation sits on the ramp. This aircraft is no longer flyable, and has been built into part of the terminal building and houses an office for Sky Training LLC.