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.

Greenwood Lake Airport covers an area of 150 acres (61 ha) at an elevation of 790 feet (241 m) above mean sea level. It has one runway designated 6/24 with an asphalt surface measuring 3,471 by 60 feet (1,058 x 18 m).

For the 12-month period ending March 25, 2010, the airport had 18,099 general aviation aircraft operations, an average of 49 per day. At that time there were 64 aircraft based at this airport: 91% single-engine, 6% multi-engine, 2% helicopter, and 2% ultralight.

When Jungle Habitat was opened in 1972, the on-field FBO offered aerial tours in Cessna 152 and Cessna 172 aircraft painted with tiger and leopard stripes.

• List of airports in New Jersey

• Greenwood Lake Airport (4N1) from New Jersey DOT Airport Directory
• Aerial image as of April 1994 from USGS The National Map
• Satellite photo of Connie on the ramp (Google Maps)
• Jetlink Aviation, a multiengine flight school based at 4N1
• FAA Terminal Procedures for 4N1, effective October 31, 2024
• Resources for this airport:
  • FAA airport information for 4N1
  • AirNav airport information for 4N1
  • FlightAware airport information and live flight tracker
  • SkyVector aeronautical chart for 4N1