AMERICANAirlines is cutting 6.4% of its worldwide economy capacity by reducing seating over the next year.
The carrier will take out two rows from economy to increase seat pitch in remaining seats to a 36ins maximum from 31-32ins.
Managing director European sales and marketing Jon Snook said: “Capacity has grown in excess of demand which is a recipe for disaster.”
UK routes will begin to see the new $70m economy layout from the autumn.
Snook said the airline was also responding to customer complaints.
He said: “The issue of seats and comfort, or lack of it, is all too familiar. People have asked for more space.”
He added there will be no fare increases.