"Robert M. Gary" wrote in
oups.com:

Even when I am being paid, its not commercial. At least in the
sense the the FAA does not require me to told a class 2 medical.
The FAA FAQ said that they consider CFIs as being paid to teach
not to fly. Perhaps we're talking semantics.

Actually no. Although the "fly for hire" has clouded the issue
somewhat, one reason that a commercial is required has nothing to do
with compensation.

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