Separate accounting records shall be maintained for each air transport entity for which separate reports to the BTS are required to be made by sections 21(g) and for each separate corporate or organizational division of the air carrier. For purposes of this Uniform System of Accounts and Reports, each nontransport entity conducting an activity which is not related to the air carrier's transport activities and each transport-related activity or group of activities qualifying as a nontransport venture pursuant to paragraph (b) of this section, whether or not formally organized within a distinct organizational unit, shall be treated as a separately operated organizational division; except that provisions of this paragraph and paragraph (b) shall not apply to leasing activities.

As a general rule, any activity or group of activities comprising a transport-related service provided for in transport-related revenue and expense accounts 09 through 18 shall be considered a separate nontransport venture under circumstances in which either: (1) A separate corporate or legal entity has been established to perform such services, (2) the aggregate annual revenue rate, as determined in section 2-1(d), during either of the prior two years exceeds the greater of $1 million per annum or one percent of the air carrier's total annual transport revenues, or (3) the aggregate annual expense rate, as determined in section 2-1(d), during either of the prior two years exceeds the greater of $1 million or one percent of the carrier's total annual operating expenses: Provided, That revenues and expenses from in-flight sales, and interchange sales shall be considered related to air transportation and accounted for accordingly, regardless of the revenue or expense standard set forth above.

The records for each required accounting entity shall be maintained with sufficient particularity to permit a determination that the requirements of section 2-1 have been complied with.