Originally Posted by FWAAA

When discussing whether it makes sense to add seats, keep in mind that the incremental seats added won't be filled every time. A lot of flights depart with an empty seat or two, which are filled by NRSA employees. Imagine paying that fourth FA to enable several extra seats that are often filled by non-fare-paying employees. Ouch!

There are other factors as well. If the airline is young and growing, then that additional FA makes substantially less money (and thus costs the airline far less money) than if the airline is old and stagnant. Until recently, AA had not hired a new (cheap) flight attendant since 2001, other than a few language speakers for China flights. So AA's cost to add an additional FA was far more than at VX or B6, where they've been constantly hiring new FAs (at very low wages). Most of AA's FAs were at or close to top of scale, which is not the case at the young, growing airlines.