Well the real ATC experts are the boys and girls at the coal face who move the traffic.
But in this context an ATC expert is a person who is expert on the systems, the processes and methods of delivery that the ATCO's need. Radar, Flight Data, Maps, software changes etc. etc. etc. If you like they are a part of the tail of the operational dog. In other terms the ATCO's are the user's of a highly complex engineering system which requires constant maintenance, tweaking and updating and ATC experts are a part of the group that likes to tweak things
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Bex:
You and I have never been in dispute about Swanwick but we do disagree about how to get things done.