Plains Airport (FAA LID: S34) is a county-owned public-use airport located one nautical mile (1.85 km) northwest of the central business district of Plains, in Sanders County, Montana, United States.

[1] According to the FAA's National Plan of Integrated Airport Systems for 2009–2013, it is categorized as a general aviation facility.

[2] Plains Airport covers an area of 259 acres (105 ha) at an elevation of 2,467 feet (752 m) above mean sea level.

It has one runway designated 13/31 with an asphalt surface measuring 4,650 by 75 feet (1,417 x 23 m).

[1] For the 12-month period ending July 22, 2008, the airport had 3,900 general aviation aircraft operations, an average of 10 per day.