FAA interpretation of the regulations governing sightseeing rides conducted in gliders

The FAA issued an internal memo concerning which FARs govern sightseeing rides conducted in gliders.

From the text:

Accordingly, an air tour conducted for compensation or hire in a glider may be conducted under the part 91 operating rules. It need not comply with the § 91.147 commercial air tour rules or the part 136 air tour rules. The operator need not hold a part 119 certificate.

The memo is located here.