The move up to an Airbus A330 means a 72% increase in available seats on each flight this summer.
It comes just over a year after the airline began its first direct transatlantic flights to New York from its new North of England hub, initially operated on a single-aisle Airbus A321LR.
Previously, the A321LR offered 184 daily seats from Manchester to JFK. This number has now risen to 317, with economy having an additional 119 seats, making 287. There are now also 30 fully lie-flat Business Class seats, an increase of 14.