A system and method to breakout and splice into optical circuits in a ribbon cable trunkline extending throughout an aircraft with optical minimal loss. Breakout boxes are positioned at strategic locations along the aircraft's fiber optic trunkline. Within each box, optical fibers in a loose bundle are permanently connected in ribbon cable form to the inner sides of cable connectors physically connected to the box, each extending through a wall of the box. The ribbon cable forms are transitioned into the fibers in the bundle, which are longer than the spacing between the cable connectors. When an optical fiber circuit needs to be broken out at the location of a particular box, the proper fiber in the bundle is cut and one or both ends that result are permanently connected to a breakout connector, also positionned through the box, so that the optical circuit appears on the breakout connector outside the box where a mating connector can be used to further route the optical circuit being broken out.