Determining the Most Significant Carrier (MSC)
The process to determine the Most Significant Carrier (MSC) is defined in IATA Resolution 302. In case of code-share flights, in general the Marketing Carrier's baggage policy prevails, unless that
carrier publishes a rule stipulating that the Operating Carrier’s baggage policy should apply.

The general rules to determine the MSC are based on the Areas where the transportation takes place.
These areas are categorized between the IATA Traffic Conference (TC) Areas and Sub-Areas as
follows:
• Traffic Conference Area 1 (TC1): The Western Hemisphere (The Americas and The Caribbean)
• Traffic Conference Area 2 (TC2): Europe, Middle East and Africa
• Traffic Conference Area 3 (TC3): Asia and Asia Pacific

Based on the above categorization the MSC is:
• The carrier performing carriage on the first sector that crosses from one Area to another for travel between two or more Tariff Conference (TC) Areas
o Exception: TC123 only, the carrier providing carriage on the first sector that crosses between TC1 and TC2.
• The carrier performing carriage on the first sector that crosses from one Sub-Area to another for travel between two or more Tariff Conference (TC) Sub-Areas
• The carrier performing carriage on the first international sector for travel within a Tariff Conference (TC) Sub-Area.