How is/was RFID bag handling introduced in a baggage handling system tailored to barcodes? I have just seen Richard Hammond's Engineering Connections about Hong Kong Chek Lap Kok (built 1998) and afterwards, Big, Bigger, Biggest about London Heathrow Terminal 5 (built 2008).

Quote from Eng. Conn.:


  Hong Kong was one of the first airports to replace bar codes with RFID tags to track bags


Quote from BBB:


  Even such an advanced [baggage handling] system [as the new one in T5] still relies on good old-fashioned Bar Codescanners.


Which made me think: Bar codes are, as far as I know, standardized by IATA, so luggage can go end-to-end through a multitude of airports on one bar code ("check-through"), but I guess when the first airport switched over to RFID, there wasn't one for RFID, so there's a bit of a hen-egg problem. How did Hong Kong airport assure that all luggage passing through it had an RFID tag?
By printing them along with bar codes. RFID mode became operational in HK in 2005. Basically, the airport replaced the barcode only baggage tags with RFID embedded tags:


  Hong Kong International Airport (HKIA) today announced that all of its check-in counters can now print integrated radio frequency identification (RFID) baggage tags. The new tags, which combine an embedded RFID chip with a barcode, are replacing barcode-only baggage tags on an airline-by-airline basis.


Basically, the system reads both the RFID tags and barcodes.