This conversation seems to re-appear around the internet periodically. Usually some random journalist seems to 'rediscover' Rule 240 in its pre-deregulation form.
According to the FAQ section at the FAA ATCSCC's website (
What's New -- Air Traffic Control System Command Center), the following is stated about this topic:
"Where can I find information on Rule 240?
The term "Rule 240" refers to a rule that existed before airline deregulation. There is no longer an actual Rule 240. The term, as it is now used, refers to each airline's "conditions of carriage" policy. You would need to contact the airlines to obtain this."