Just spotted a blocked flight on flightradar24.com. It's blocked literally: only minimal data, no ICAO hex code, and a callsign shown is... "BLOCKED"
http://www.flightradar24.com/BLOCKED/4cf1245
It comes from Seattle, Washington, US, flew over the ocean and currently (1310Z) it's over northwest Spain.
Any idea what could it be? TIA!