It's nothing more than playing catch up. I'm company X and I managed to build an aircraft for a certain mission at the lowest ever MTOW. Company Y will try to get down to that MTOW to be able to compete. Check the MTOW of the Airbus A320-100 and the Boeing 737-400, to save you time, they are 200 pounds apart. But the A320-100 didn't sell well, the A320-200 did. Guess what, the 737-800 [matches that weight][1]. Now there's something called [Weight Factor][2]. It's **SQRT(MTOW/50)**, MTOW in kg, thank you. The Weight Factor is a vital part of calculating the charges the plane pays everywhere around the whole, for taking off, landing, and just flying en-route. The only interesting thing about **10,600 lbs / 4,800 kg** is that the weight factor is kept a tad under 10.00 (two decimals are used in WF). Now is there a higher charge for a plane with WF above 10.00? I scoured the internet, there doesn't seem to be WF brackets set that way. I very badly wanted to find something. Maybe it's there. I don't know. For big planes, there seems to be, Ryanair has a fleet specifically made with a certified MTOW under 70,000 lbs for similar reasons [apparently][3]. [1]: https://en.wikipedia.org/wiki/List_of_airliners_by_maximum_takeoff_weight [2]: http://www.eurocontrol.int/articles/establishing-route-charges [3]: http://www.pprune.org/tech-log/494333-ryanair-mtow-66990-how.html