GPS Block IIF, or GPS IIF is an interim class of GPS (satellite), which will be used to keep the Navstar Global Positioning System operational until the GPS Block IIIA satellites become operational. They are being built by Boeing, and will be operated by the United States Air Force following their launch by United Launch Alliance, using Evolved Expendable Launch Vehicles. They will be the final component of the Block II GPS constellation to be launched. On February 5, 2016, the final satellite in the IIF-block was successfully launched, completing the block.