Abstract: A method of deploying a cable or other line in a fluid transportation pipeline while in normal operation full of and transporting a fluid under a positive pressure. A collapsible centralizing device is attached to the leading end of the cable and is then fed in a collapsed state into the pipeline via a first fluid sealing means at the cable entry position. That device maintains the cable end centralized in the pipeline cross section while the cable is fed into the pipeline. Magnetic sensing means disposed near the cable exit position sense the presence of the cable end and control the cable infeed so as to position the cable end in a predetermined cable retrieval position. A tubular lance is fed into the pipeline through a second fluid sealing means disposed at the cable exit position, and a grab housed in the nozzle of the lance is ejected to engage and capture part of the centralizing device and cable end, whereafter the grab closes on being drawn back into the lance.