The main thing to take away from this section is that excess baggage is very expensive. The standard charge for excess baggage is one percent of the full first class fare per excess kilogram (even if you are traveling on a discounted coach-class ticket), payable separately for each flight.  If you must take excess baggage on some portion of your trip, check with the airlines in advance: particularly on flights to and from North America, some airlines charge a flat rate per piece (typically $100-$125) which is substantially lower than the per-kilogram charge.

Airlines are not required to accept excess baggage at all.  On some flights operated by small planes, such as to African safari camps or short, island or mountain airstrips, they simply don’t have room for it and won’t carry it at any price.  Nor will excess baggage, even if paid for as “accompanied” baggage, necessarily be put on the same flight with you, although airlines have no reason not to and usually will, space permitting. Unaccompanied baggage is considered “air freight” and charged at cargo rates.  Air cargo rates are higher per kilogram per kilometer (or per pound per mile) than most coach rates for passenger transportation.