I attended a presentation at Popham by PilotAware about a free upgrade that should be available by the end of this month May 2019. Anyone who uses PilotAware will know that it can pinpoint aircraft that have PilotAware or ADS-B transmitters and also gliders equipped with FLARM. The weakness in the system is pinpointing aircraft that only have transponders.Mode S provides height but not position however the people at PilotAware have devised a way of estimating the position of mode S aircraft using triangulation from a network of ground stations installed at an expanding number of airfields. They have been installing them at the rate of two a week. The computer hardware is provided free but the airfield has to pay the cost of the aerial and installation which is a couple of hundred quid or so.The ground stations receive mode S transmissions from aircraft transponders, communicate with each other to triangulate the positions then broadcast this information to the PilotAware equipped aircraft. That's a lot of processing.Between aircraft and ground stations it is at the speed of light but between the ground stations it is at the speed of the internet. This coupled with the frequency of transponder signals, equates to a latency (delay) of a few seconds. PilotAware have run tests and found that 97% of signals are processed within 4 seconds with most of them being processed within 2 seconds. So PilotAware can locate an aircraft that is transmitting only mode S, to a circle of sky around 2 to 4 seconds in diameter which, even for traffic only 1 mile distant travelling at 120mph, equates to just a few degrees of your field of view.If you have a traffic service from ATC they will give you locations based on the clock, each hour being 30 degrees. The accuracy of the PilotAware system will be well within this 30 degree field of view so can be considered as reliable as or better than an ATC traffic service. I am eagerly awaiting this upgrade.