According to the U.S. Census Bureau, the county has a total area of 685 square miles (1,770 km2), of which 681 square miles (1,760 km2) is land and 3.8 square miles (9.8 km2) (0.6%) is water. It is the fourth-largest county in Tennessee by area. The county is located atop the Cumberland Plateau.
Revenue passenger kilometres (RPK) is a measure of the volume of passengers carried by an airline. A revenue passenger-kilometre is flown when a revenue passenger is carried one kilometre. A passenger for whose transportation an air carrier receives commercial remuneration is called a revenue passenger.
Process Performance Index (Ppk, Cpk, Pp) Process performance index, is a statistical tool to verify if the sample that have generated from the process is capable to meet the customer requirement. It measures the performance of the process related to both dispersion and centeredness.