Checked baggage, when used in connection with air travel, means those items of baggage which are delivered to the operating airline for transportation in the hold of the aircraft and which is inaccesible to the passenger during flight.
This baggage is limited by airlines with regards to size, weight and number, usually dependent upon the fare paid or class of travel concerned. Baggage exceeding these limits is regarded as excess baggage.
Should passengers having checked baggage not arrive at the departure gate before the flight is closed, the passenger will be offloaded from the flight and baggage must be retrieved from the aircraft hold before the flight is permitted to be dispatched. This is the cause of many delays but is necessary for security reasons to prevent baggage being checked-in without the passenger physically being onboard the same aircraft.
Excess baggage is the amount of baggage which is in excess of the free allowance in size, number or weight permitted for the air journey at any particular time. At the airline's discretion, this may be carried at an extra charge but no guarantee is made and it could be subject to being sent as