The International Air Transport Association (IATA) has recommended smaller carry-on baggage to optimise space in cabins.
Developed in partnership with several member airlines and aircraft manufacturers, IATA's suggestion for optimum size carry-on bags is 55 x 35 x 20cm (or 21.5 x 13.5 x 7.5 inches).
The trade association believes that if these guidelines were adopted as an industry standard, every passenger should "theoretically have a chance of storing their bags onboard aircraft that offer 120 seats or more".
Thus far, Lufthansa and Emirates have confirmed that they will adopt the new guidelines.
But the IATA's recommendation is significantly smaller than the existing maximum cabin bag size at many airlines. For instance, British Airways and Easyjet both have a maximum size of 56 x 45 x 25 (22in x 18in x 10 inches).
Tom Windmuller, IATA's senior vice president for airport, passenger, cargo and security, said: "We know the current situation can be frustrating for passengers. The development of an agreed optimal cabin bag size will bring common sense and order to the problem of differing sizes for carry-on bags."