Airlines say their goal is to preserve, or even increase, passenger comfort. Skeptics suggest that airlines simply want to lighten the load on planes while cramming more seats onto a flight. Who is right?

It's no secret that airlines are looking for ways to maximize the yield on each flight. That is, they want to get the most revenue possible from each and every seat on an aircraft and increasing fares doesn't always do it. So, some airlines put more seats in by placing rows closer together; others remove galleys and other structures once reserved for the days when meals and other services were plentiful, in order to fit more seats.

Will passengers notice this aerial game of musical chairs? Not in all cases. As the airlines add seats to their planes, the assumption is that passengers will be crammed even further. However, through some clever arrangements, passengers may not see their knee-to-seatback ratio reduced much, if at all. This is done through some clever engineering. Cathay Pacific, for example, features economy seats that are contained in a "shell" and mimic a reclined position by allowing the seat bottom to move forward, sliding the seated passenger downward and forward as opposed to having the back of the seat swing backward. The advantage of not having the seat back in front of you intruding on your limited space is appealing, however some taller passengers have found that the "slouched" position the seat creates is not very comfortable for them.

American Airlines' latest generation of Boeing 737s will feature more seats, but thanks to the "thin is in" trend, the airline insists that the legroom will not be compromised. The airline is achieving its largest-ever seat capacity in the 737 family by removing the no-longer-needed cart storage spaces in economy and by installing thinner seats that "recline" by pivoting the seat bottom forward slightly. If you have to use a computer to give your verdict on these seats, American will feature power ports at every seat on its newest 737s plus additional overhead space. Is this a consolation prize? You be the judge. Interestingly, American will have to add an additional flight attendant on the higher-capacity planes due to a federal regulation that requires a flight attendant for every 50 passengers.

Earlier this year, Air France introduced thinner seats on its short-haul, all-economy aircraft (Airbus A391, A320, A321). The seats feature a trade-off. They allow the airline to add an extra row to the A320 and A321 aircraft and offer passengers added legroom but offer little to no recline in return.

Whatever the motivation – lighter seats, less fuel burn, more revenue – the moves clearly benefit the airlines more than the traveler. Unless aircraft cabins get wider, don't expect anything to be done about the width of seats anytime soon.