In 1982, a prototype standing skyline cable system was developed and demonstrated in several locations around Vermont. The system was designed to extract low quality trees from the forest leaving the better trees with more room to grow. Lifting trees from the forest with aerial cables eliminated potential soil compaction, erosion, and damage to the best trees that were left to grow. Also the system required much less power and about 1/7 the amount of fuel than conventional ground skidding because no heavy machinery had to be driven via indirect trails into the woods. This system would have been commercially viable if it had been used to access high value timber that was inaccessible to conventional equipment, but the goal was to improve forests by removing low value trees. It was nearly economically viable for extracting low value trees, and would have been profitable if there had been a way to be compensated for the net present value of increased future value of a carefully thinned forest.
This said, the system had several shortcomings. To save cost, the skyline was stored on a wooden reel which was very time consuming, but with a little more money the system could have been fitted with a powered skyline storage drum. The dual winch drums were controlled by clutches and brakes with one drum paying out cable while dragging the brake and the other winching in. With considerably more money, it would have been worthwhile to develop a system that would have allowed much smoother and faster sychronized winch operation without the need to drag brakes and feather clutches. Setting up the system took a considerable amount of planning and time, and required skills that few people had. A report on the project is available at archive.org/stream/VermontCab...
Now, 35 years later, with advances in technology, a semi-automated skyline system could be developed that would be easy to set up, simple to operate, and less expensive.