Used to work for a company developing ATC systems. As stated before, the only provider that we used was IER. Coincidentaly there is one of their printers (non-functional) on ebay!
IER-512-Thermal-baggage-tag-flight-strip-printer
These are very simple printers that are controlled using ascii characters and control sequences, so basically all you require to do is create a text file or text string and send it to the printer via a COM port. There may be a driver for Windows but we never hosted on it, so don't know!
Internally the printer is very 'heath-robinson' - there are guides that you can set for your selected strip width. Considering the size of the printer casing, there is very little inside, however they are built to last so are quiet heavy! From memory I would estimate the size as 22cm w x 22cm h x 45cm d.
Depending on our customers' choice we used roll or fan-fold strips. There is a cutter mechanism to use with roll feed and IIRC a sensor to detect strip start on fan-fold.