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.
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.
Originally, the aerodrome consisted of a 1,200 by 30 metres (3,937 by 98 ft) section of the island's dirt road.
This was chosen to reduce the bureaucracy of construction.
It has a 1,500-meter (4,921 ft) dirt runway numbered 06–24.
The airfield was built in connection with the LORAN-C transmitter at Olonkinbyen and was completed in 1960.
This can cause sudden change to the wind direction on the island.