Bob Gardner wrote
I can't find anything in Part 121 to support this assertion...but
maybe I'm not using the correct search arguments. Do you have a
regulation citation?

I think that this is what John is talking about:

http://www.faa.gov/library/manuals/e...volume2/media/
2_076_00.pdf

D. Airport Operations. An operator/program manager must conduct a
representative number of proving tests into airports that the
operator/program manager plans to serve in approved OpSpecs
scheduled/unscheduled or approved MSpecs operations. If an operator/program
manager plans to provide service to airports in more than one area
(domestic and overseas), the operator/program manager must conduct proving
tests into a representative number of those areas. The Administrator will
determine what constitutes a representative airport or area of en route
operation.

We used to call them 'Proving Flights'. I have flown them for 3-4 newly
certificated airlines.

Bob Moore