but this data shouldn't be available to Flightaware and neither so soon
The graphic was from FlightAware using data from the FAA's Surface Movement Event Service
Yes, this system is designed to alert to conflicts from traffic on approach and ground operations.
Still does not explain where this "to the foot-precise" altitude or height comes from
Please read the links provided showing the capability and expectations of the system before responding. (data is used from the terminal radar system)
The cost-effective alternative to the ASDE-3/AMASS capability, referred to as ASDE-X, is one of the first new runway safety program technologies aimed at improving ATCS situational awareness by providing tools to supplement their tasks (McAnulty, Doros, & Poston, 2001). The data that ASDE-X uses comes from a surface movement radar located on the airport traffic control tower or remote tower, multilateration sensors, ADS-B (Automatic Dependent Surveillance-Broadcast) sensors, terminal radars, the terminal automation system, and from aircraft transponders. By fusing the data from these sources, ASDE-X is able to determine the position and identification of aircraft and vehicles on the airport surfaces, as well as of aircraft flying within 5 miles (8 km) of the airport (selectively up to 60 nmi).
As many are aware, I have not been a proponent of the ADSB or Mode S for this type of use, due to the accuracy issues, especially on descent.
That being said, this is the data that the FAA system provides, by whatever means.
That also being said, that is my question on validity of the alert capability of the systems already in operation.