In 2006 Boeing began using a moving assembly line for the first time to build its market-leading 777 jetliner. At first, the moving assembly line was used only during final assembly positions for the airplane, moving it at a steady pace of 1.6 inches per minute during production. To make its 777 assembly line move during final assembly, a tug is attached around the front landing gear of the airplane and pulls it forward. The tug has an optical sensor that follows a white line along the floor. A continuous, one-bay moving assembly line for the 777, which will include systems installation, final body join and final assembly for the airplane, is scheduled for sometime in 2008. This will be the most extensive moving production line used to build a commercial airplane.