There was a feature request many years ago for the ability to overlay several different flights (for example, from the same aircraft on different dates) on to a single map. Did that ever gain traction?
If you want to play with something like that, you can pull up a flight and download the KML in Google Earth format. I have not tried, but I imagine you could load several flights in. It does not have the same appearance as FA, but it does the job. If you want to get closer to FA, you could try to use VRS (http://www.virtualradarserver.co.uk/) to generate the graphics with multiple flights.
VRS is something I have been wanting to play with, but have not yet had the time.