Directional control was a piece of technology essential for driving safely to a destination in time travel.
When Omega converted the star Qqaba to a black hole as a power source, it was a missing piece of the research of the Gallifreyans about time travel. It was implemented in a device along with the time-jumper of Fenris, a member of the Order of the Black Sun. He was sent thirty thousand years back to the early times of Time Lord civilisation, to sabotage their achievements in the field. Rassilon stopped his attempt and separated him by his directional control device. Without it, Fenris was splintered into the time vortex after the time jump. Eventually, Rassilon took the device with the intention of studying its operating principle. (COMIC: Star Death)