Will push to shrink airline carry-ons really fly?

The International Air Transport Association (IATA) is backpedaling a bit on the "initiative" it announced last week that would have air passengers switch to smaller carry-on bag sizes, after the group came under criticism that the move was primarily designed to create more revenue for the airline industry.

At the time IATA, which represents about 260 airlines, said its members had come up with an "optimum size guideline" for carry-on luggage to make the best use of cabin storage space.

According to the new guidelines, the new size for carry-ons would be 21.5 x 13.5 x 7.5 inches (55 x 35 x 20 cm) in size.

Those new dimensions are significantly smaller that what's currently considered acceptable for an airline carry-on bag -- nearly 40 percent smaller than previous IATA standards or, according to Quartz.com, "the equivalent of four soccer balls' worth (of) volume."

"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," Tom Windmuller, IATA's senior vice president for airport, passenger, cargo and security, said in a press statement at the time.

"We know the current situation can be frustrating for passengers. This work will help to iron out inconsistencies and lead to an improved passenger experience," he added.

But industry observers, as well as some U.S. lawmakers, are taking IATA to task for the new baggage standards.

"Once again, the airlines find a way to make their problem the passenger's problem -- and an expensive problem at that," travel industry consultant Henry Harteveldt told Australia's news.com.au.

"If our luggage has to go on a diet, let's make sure the result isn't another airline industry profit binge," Sen. Bob Menendez (D-N.J.), Ranking Member on the Senate Banking Subcommittee on Housing, Transportation, and Community Development, said on his official website.

"This must not turn into another industry ploy related to baggage fees since dubious tactics, like hidden fees, are already used to trick consumers."

Menendez, along with other Senate colleagues, sent a letter on Tuesday to the CEOs of major U.S. airlines, which read in part, "Traveling with luggage is a basic component of air travel and almost always a necessity -- not a luxury...If your airline intends to reduce the size of carry-on bags allowed in the cabin, we expect that you will mitigate any additional costs to customers by allowing them to check their luggage without charge."

"Enough already," said Sen. Charles Schumer (D-N.Y.) in a press statement issued Monday."The airlines already charge more for checked baggage, pillows, peanuts and head phones. It's got to stop somewhere."

Schumer said if the proposed baggage standards become a reality, air travelers would need to spend hundreds of dollars on new luggage that meets the "IATA Cabin OK" dimensions. And many others would be forced to check their bags: A once-free service that, according to the U.S. Bureau of Transportation Statistics, earned the biggest U.S. airlines nearly $3.5 billion in revenue in 2012.

The IATA, meanwhile, issued a clarification late last week -- emphasizing that its Cabin OK dimensions were guidelines and not standards -- and that maximum size limits for baggage are set individually by each airline.

"Cabin OK will give passengers greater certainty that their carry-on bag will be accepted in the cabin," the press statement on the issue continued.

"A typical fully booked narrow-body jet aircraft is not able to accommodate a bag for every passenger on board at maximum size limits. On-time departures suffer as airline staff search for passengers willing to put their bag in the hold."