Contractors use compressed air to blow rope or line through the conduit and “fish” the fiber cable back through. In this method, the cable is. Back in the early 1980s, when everything in fiber optics was changing rapidly - even more rapidly than today - British Telecom came up with a different idea. The pushing force is. In fiber optic cable blowing, high-speed airflow is combined with a mechanical pushing force to produce the installation, known as blowing or jetting. Air blowing fiber, also known as jetting fiber, is an efficient way to install fiber optic cable and facilitates future expansion of optical fiber networks. Often you'll see large poly conduit spools on roadsides, highways and interstates all.