The are rules pertaining to the carriage of baggage on all airlines. Invariably, you would come across different types of restrictions and limitation when it comes to baggage matters. Generally, these pertain to the dimensions of the luggage, weight of bag, number of pieces to be carried and sometimes, time-restrictions for which the allowance is allowed. Whether the baggage to be carried is free of charges (and to what extent) or whether it is to be charged, varies from carrier to carrier. But, this is a certainty that these can not deny the carriage of bags on board, whether as hand or as checked in luggage.
For the American Airlines (AA), which is one of the top airliner of USA, there are rules pertaining to these allowances. After its merger with the US Airways, AA has also aligned these policies with those of the merged entity.
AA charges for every bag that you check in. These vary depending upon the ordinal number of the bag to be carried (meaning that the first bag will have a different rate than the second, third or fourth bag) and the destination country or region. However, for certain special guests, it allows carriage of complimentary bags which are allowed without any charges. The charges as well as the rules of complimentary bags are mentioned in the American Airlines baggage allowance. So, certain types of guests such as AAdvantage Gold, Platinum and Executive Platinum members; oneworld Ruby, Sapphire and Emerald members; Alaska Airlines MVP, MVP Gold and MVP gold 75k members; and certain Credit Card holders do have advantage of carrying these complimentary bags on their domestic or international flights.
There is a limit on maximum number of bags that can be carried checked in on AA. 10 bags are allowed for domestic, transatlantic and transpacific flights whereas 5 bags are allowed on flights to Mexico, Caribbean, Central America, South America and Brazil.
Further, each bag shall be of maximum 23 kgs weight and 158 cms sum of dimensions, except for flights to/from Brazil where allowance is 32 kgs per bag with 158 cms dimension limit.
There could also be seasonal variations to these rules, making allowances more relaxed during certain parts of the year or for some special destinations or even when there is a need for promoting any new destination. All these are discretionary matters for the carrier but the standard allowances and rules remain the same for most of the time of a year.
Post merger of US Airways, these rules for US Airways would be the same as that of AA except for those flights whose tickets have been issued before 23 April, 2014 for which the US Airways allowance rules will be applicable.