Why airlines have weight restrictions on hand carry and check-in luggage

Nowadays, people do complain about airline policies calling it "outdated" without understanding the rationale behind them all. We now explain why there are certain weight restrictions for hand-carry items and check-in luggage. We also explain why passengers are charged "excess baggage" fees which are actually high but reasonable if we are to look at the facts behind. We hope this would give a clearer understanding on hand-carry items.

Gary Sato
There are two types of baggage that passengers carry when they fly, and these are check-in luggage and carry-on or hand-carry luggage. Taking it by their names, check-in luggage are those items that are to be stored at the cargo-hold of the aircraft. Carry-on or hand-carries are those that, we do carry on board!

Checked-in luggage has to be within the weight limits to ensure each piece is within the safe limits for manual handling. This known weight eats into the aircraft's takeoff weight calculation, leaving less for cargo.

Also as airliners are designed to take off with one failed engine and carry reserve fuel in the unfortunate event of failures and diversions, this extra power works as the weight safety margin when nothing fails. In practice weight margins rarely get pushed - most flights are volume-limited, with enough weight margin to take off at reduced power.

​If an airplane is too heavy when it tries to take off, it might not be able to fly safely. Though it may still lift off, but it may not also be able to maintain flight in the event of an engine failure.

Additionally, the weights of the things that can render an airplane overweight (mainly passengers and their baggage) are not necessarily centered within the airplane's safe center-of-gravity (CG) range; thus, overloading a plane with passengers and baggage could potentially move the CG beyond its forward or aft limits, resulting in loss of control upon lift off or shortly afterwards.

More weight means more power on the engines needed during take-off which means higher fuel burn. Higher fuel burn means higher costs for the airline, and fuel usually accounts to about 30% of the airline's expense.

So why do the weight limits of carry-on luggage vary per airline even if they use the same type of aircraft?

Luggage shares its volume with cargo, which airliners from the A320 up are designed to carry in the hold. Lately, cargo tends to get become more profitable than passenger service.

The A320 is 42.6 tons empty, but does not matter much. What matters more though is its 78 tons MTOW or Maximum Take-Off Weight and the weight of passengers plus their hand-carry luggage take more of these, leaving the rest for cargo. Since airlines also make money from cargo, they have to ensure that there is enough space allocated for these after passengers and their luggage have been factored in. Remember, an aircraft has only up to a certain MTOW. Beyond that would be risky.

So now for example, passenger D flies. Allowable carry on is 7kgs, with 2pcs 25kgs of check-in luggage. Passenger D carries two check-in baggage 20kgs each and a hand carry of 10kgs, meaning, he still has 5kgs of weight in his check-in luggage but exceeds the 7kgs of carry-on allowance. Will it make a difference since the total weight of his luggage is just 30kgs versus the 57kgs allowable total weight? Yes, because the weight of carry-on items are computed based on their assumed weight and not actual weight, and if an aircraft will be carrying 175 passengers lets say for an Airbus A320, that will be computed as the passenger assumed weight plus 7kgs for each carry-on item allowance multiplied by 175. At the same time, there is also a safety margin on the overhead bin's allowable weight it can carry safely. So to ensure safety and a correct weight - balance, passenger D has to shed off some weight from his carry-on luggage and move them to the check-in luggage which still have space for 5kgs each.

Airline policies are written down not just to make money and to augment costs, but a lot has got to do with safety reasons. There are also various reasons why different airlines have different weight policies and they all depend on the market. Always remember that Filipinos love bringing home balikbayan boxes and pasalubongs which usually go unto the cargo hold of the aircraft. Hence, weight restrictions have to be properly implemented. Why does Delta have no maximum weight for carry-on items? Well apparently, they still do at selected destinations namely Singapore, Beijing, and Shanghai. The maximum carry-on item is 7kgs,

Last but not least, MOST airlines have carry-on luggage weight restrictions!

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