Interesting article on the BBC News website.  UK air traffic service is soon to trial a new way of spacing aircraft coming into land at London Heathrow, using time rather than distance as the control.  It's believed it could reduce delays caused by wind factors.  Link: http://www.bbc.co.uk/news/magazine-31109732

This is nothing new. For example KFDW tower(s) have employed a software tool called CTAS that allows them to schedule landing aircraft by time. Some other very busy airports in the US use it as well. There is attempt to also introduce time-based metering to the enroute flight phase, lots of research is being conducted on the subject by NASA/FAA.