premise: Donaldson Center Airport (IATA: GDC, ICAO: KGYH, FAA LID: GYH) is a public airport six miles (10 km) south of the central business district of Greenville, a city in Greenville County, South Carolina, United States. It located at the Donaldson Center Industrial Air Park and is owned by the City and County of Greenville.
hypothesis: Donaldson Center Airport is located in South Carolina, six kilometers south of the central business district of Greenville.
reason: "Donaldson Center Airport [...] is [...] six miles (10 km) south of the central business district of Greenville, a city in Greenville County, South Carolina" is a given fact, stating that it is 10 km south, whereas I said it was 6 km south, making my statement definitely incorrect. I think the system had difficulty because it probably assumes that miles and kilometers are the same, or it doesn't understand that "km" means "kilometers". 