Big Sky Airport (ICAO: KEKS, FAA LID: EKS) (also known as Ennis Big Sky Airport) is a county-owned, public-use airport located six nautical miles (7 mi, 11 km) southeast of the central business district of Ennis, a town in Madison County, Montana, United States.

[3] Big Sky Airport has one runway designated 16/34 with an asphalt surface measuring 7,600 by 100 feet (2,316 x 30 m).

[1] For the 12-month period ending July 21, 2019, the airport had 12,350 aircraft operations, an average of 34 per day: 93% general aviation, 6% air taxi, and <1% military.

[1] Choice Aviation, the airport's fixed-base operator (FBO), offers fuel, flight instruction, aircraft/hangar rental, and other services.

On 19 February 2020, Big Sky Airport was awarded a $5.6 million FAA grant to extend the main taxiway to 7,600 ft (2,316 m), repave portions of the runway, and expand the airport property.