To be clear, this is a very complex and sophisticated system with more than a million lines of software. This is not simply internal telephones, it is the system that controllers use to speak to other ATC agencies both in the UK and Europe and is the biggest system of its kind in Europe.
H'mmm. But how many bugs?
See
here for the source of that (badly written) piece ... which was obviously dished up by "PR" folk with limited grasp of anything more technical than the office coffee maker (if that). Who else would say "lines of software" instead of "lines of computer code"?
