Unintended consequences sometimes happen many years after. In selling HMAS Melbourne (above) - a very old aircraft carrier to China for scrap in 1985 Australia likely made a mistake in including some essential flight operations gear - old for us but a windfall technological gain for China. Along with some Russian flight operations gear the Australian-UK originated gear may well have helped China in in its construction of its new large aircraft carrier - the Liaoning.
Sensitive arrester cable and mirror landing gear technology was attached to HMAS Melbourne when it was passed to China. HMAS Melbourne was meant to be scrapped by China immediately, but instead China studied then most probably reverse engineered the arrester cable and mirror landing gear.
Top view diagram (above) of HMAS Melbourne's arrester gear donated to China.
China's Liaoning (artist's conception of what it will look like around 2017 above) has performed several Shenyang J-15 (navalised Russian Flanker equivalent) jet arrester gear landings, some ski-jump assisted takeoffs and "sailed" for a few hours using its oil-conventional propulsion. It will probably be 3-4 years before it begins regular trials with around 40 jets. Then it will be fully in-service operational by 2020, if not earlier.
With blast shield up a J-15 is about to take off, assisted by the Liaoning's bow "ski-jump'. With the ski-jump there is probably no need for catapults (none appear to be fitted).
A report from [Taiwan's] Central News Agency of November 26, 2012 indicates:
"...China emphasized Monday that the arresting gear used to conduct China's first landing of a fighter jet on the aircraft carrier Liaoning was developed on its own...the Chinese Navy said on its website that the arresting gear was made by China with its own technology because Russia refused to sell it to its southern neighbour...All countries that own aircraft carriers keep the sophisticated technology used in their arresting gears a secret."
However, an exception appears to be Australia passing "secret" arrester gear technology to China.Australia's former light carrier HMAS Melbourne was sold to China in 1985. This sale included the Australian (or UK designed?) arrester gear going to China .
On arrester gear going to China see the wiki entry. Former HMAS Melbourne's steam catapult, arresting equipment and mirror landing system were not removed. At this time, few western experts expected that the Chinese Government would attempt to develop aircraft carriers in the future.
Wikipedia, based mainly on Hemmingsen's research, further reports:
Once in China the former HMAS Melbourne was not scrapped immediately; instead she was studied by Chinese naval architects and engineers as part of the nation's top-secret carrier development program
However, it is unclear whether the Chinese Navy orchestrated the acquisition of Melbourne or simply took advantage of the situation; Rear Admiral Zhang Zhaozhong, claims that has stated that the Chinese Navy was unaware of the purchase until Melbourne first arrived at Guangzhou.
Melbourne was the largest warship any of the Chinese experts had seen, and they were surprised by the amount of high-tech equipment left in place by Australia. The Chinese Navy subsequently arranged for the ship's flight deck and all the equipment associated with flying operations to be removed so that they could be studied in depth.
Reports have circulated that either a replica of the flight deck, or the deck itself, was used for clandestine training of Chinese Navy pilots in carrier flight operations."
It has also been claimed that the Royal Australian Navy received and "politely rejected" a request from the PLAN for blueprints of the ship's steam catapult.
Storey, I and You, J. 2004 "China's aircraft carrier ambitions: seeking truth from rumours", Naval War College Review 57 (1): 77–93, (Winter 2004). ISSN 0028-1484. http://www.usnwc.edu/getattachment/ffc60b3e-d2e6-4142-9b71-6dfa247051f2/China-s-Aircraft-Carrier-Ambitions--Seeking-Truth- . Retrieved 25 October 2009. p. 79
Hemmingsen, Torbjørg 2012 "PLAN for action: New dawn for Chinese Naval Aviation", Jane's Navy International (June 2012)