"Thomas Borchert" wrote in message
...
Peter,

which display aircraft
registrations do it by containing software and database to decode the
24-bit code.


Why wouldn't they simply use the flight ID data field?

For one, not all ModeS transponders have that capability as it's implemented
as a level 2 function. I know that many, if not all, areas of western
Europe require a ModeS transponder, but I'm not sure if they require a level
2 ModeS transponder.