Q. List of Airlines by Carrier Group
You can find a list of the most current BTS air carrier groupings in Accounting and Reporting Directive #299, effective January 1, 2012: http://www.bts.gov/programs/airline_information/accounting_and_reporting_directives/number_304.html
The 2011 groupings can be found in Accounting and Reporting Directive #299, effective January 1, 2011: http://www.bts.gov/programs/airline_information/accounting_and_reporting_directives/number_299.html
More Accounting and Reporting Directives can be found at http://www.bts.gov/programs/airline_information/accounting_and_reporting_directives/
For historical Air Carrier Groupings Accounting and Reporting Directives from 1990 to 2002, please download the attached file.
More BTS airline information can be found at http://www.bts.gov/programs/airline_information/