Jan Mayensfield (ICAO: ENJA) is an aerodrome serving Olonkinbyen in Jan Mayen, Norway. Operated by the Norwegian Armed Forces, it serves the island's only population at the combined military and meteorological station. It has a 1,500-meter (4,921 ft) dirt runway numbered 04–22.

The airfield was built in connection with the LORAN-C transmitter at Olonkinbyen and was completed in 1960. Jan Mayensfield is served eight times per year by Lockheed C-130 Hercules aircraft of the 335 Squadron from Bodø Main Air Station, which provide supplies and change crew at the outpost. The nearby Beerenberg volcano can cause a Kármán wind, which creates difficult landing conditions.