A related question. What impact would it have to make planes with wider seats? Say add two inches to each seat and anopther 2 inches to the aisle. Total expansion 14 inches. What would that require if done only on new construction? Gas?
Coach class on the Boeing 787, for example, will be available in either a 3+2+3 seats per row arrangement with seats almost 19 inches wide or a 3+3+3 arrangement with 17 inch seats.
19 inch is similar to a 777, which is remarkably comfortable. 17 inch is narrower than a 737, which would truly suck.