FlyerTalk Evangelist
Join Date: Mar 2001
Location: Fort Worth TX
Programs: Earned status with AA, DL, SPG, HH, Hyatt, Marriott, Seabourn, NCL, National, Hertz...I miss my bed!
Posts: 10,927
My theory is that the old Reno Air planes have more rows of F than the AA configurations.
In order to keep numbering consistent (and not skip rows), the AA planes have to start with 3 and end with 6 so that both coach sets can start with 7.
I'm sure this makes life easier for folks who end up with an unexpected equipment swap.