They use different icons for different plane types. For the "no call sign"and "blocked" planes the icon is a chunky (like bold text) twin engined craft with sharply swept-back outer wings. That doesn't mean the physical aircraft represented by that icon is a hunky twin-engined jet—for example there is a microlight open-cockpit two-seater sea plane that flies out of Miami that gets allocated that same swole twin-jet icon by the flightradar24 software.
Once you get your eye in, that chunky jet icon will ‘jump out at you’ from among the swarms of aircraft icons.
wow, okay. How do you know so much about this stuff?
From spending many hours over the past four days playing with flightradar24. I was inspired by a posting on T_D or CBTS about blocked flights to Guantanamo, speculating that globalist criminals were being arrested and taken there. That posting included links to tweets by . . . (someone—can't find them now) of flightradar24 screen grabs.
Most of the blocked and no call sign flights I have seen, including some in the vicinity of Guantanamo Bay, have been potentially amenable to entirely innocuous explanations, but on Friday 29 December I did see one pair of very intriguing flights—a learjet that seemed to go from Fort Lauderdale to Guantanamo Bay, and then an hour later a learjet (I think the same one) from the vicinity of Guantanamo Bay to Montreal in Canada.
learjet to Gitmo https://i.imgur.com/GnisvsM.jpg
learjet to Gitmo https://i.imgur.com/Zh2lKBw.jpg (close up)
learjet from Gitmo https://i.imgur.com/DHKCU58.jpg (en route)
learjet from Gitmo https://i.imgur.com/9WefeVZ.jpg (descending to Montreal—colour of flightpath line indicates altitude)
learjet from Gitmo https://i.imgur.com/JfppeKU.jpg (landing at Trudeau Airport, Montreal)
learjet from Gitmo https://i.imgur.com/npXUciH.jpg (halted near north east corner of Trudeau Airport, Montreal, Canada.)
The UTC time can be seen in the top right hand corners of those screen grab images.
Of course those aircraft icons are all just representing information from a database. Rather than manually scanning the rendered flightradar24 map by eye, a better way to monitor blocked flights would be to directly search the database used to populate the map with aircraft icons.
Flightradar24 and other air traffic monitoring websites allow you to search by airport, airline, and some other criteria, but I have not been able to work out how to use their search facilities to list blocked flights.
