Reston VA 60,000 ft at 0 knots?

[Gosell]

I set up a filter to isolate HBAL Loon balloons over South America and noticed an airliner icon near Washington DC listed as 60,000 feet and 0 knots. Any ideas?

 

[Lee Armstrong]

I would suggest that this (being so close to an airport) is a ground station used for on airport MLAT.

 

[NeoDude]

SSR Site Monitor.