The interesting thing I find here is the economics of this decision. Using Air Canada 777 as an example from SeatGuru http://www.seatguru.com/airlines/Air_Cana

The interesting thing I find here is the economics of this decision. Using Air Canada 777 as an example from SeatGuru http://www.seatguru.com/airlines/Air_Canada/Air_Canada_Boeing_777-300ER_77W_new.php http://www.seatguru.com/airlines/Air_Canada/Air_Canada_Boein... Adding the 9th seat per row results in an extra 43 seats per plane. Factoring in only the economy section of the plane, there are 344 seats in the 8 seat configuration, 387 in the 9 seat. Estimate a long-haul flight costs $1000, that makes an easy calculation of $43,000 extra revenue for the airline. That is only an extra $125/seat in revenue compared to the 8 seat configuration. Apparently it costs 1 gallon of fuel/pound on domestic flights, so let's say is 30% more on long haul flights and the average person including luggage weighs 200lbs (170lbs for the person plus 30lbs luggage). Jet fuel is currently $2.92/gallon, so let's say the airline buys it at a reduced rate of $2.70, and our 30% brings us to $4.00 per person. I'm guessing this is much of what airlines are doing with Premium Economy, but you pay a $300+ ticket difference per seat, so for each row in Premium Economy, the airline is making $1000 extra profit over the same row in Economy.