 These seats may or may not feature moveable headrests, and generally do not feature adjustable lumbar support.A newer innovation by Zodiac Seats U.S. (formerly Weber Aircraft LLC) is an articulating seat bottom, where the seat bottom moves forward in addition to the seat back tilting backwards.Such seats have been installed in some of the aircraft of Aer Lingus, Delta Air Lines, Emirates, American Airlines, and Avianca, amongst others.