Delta is investing an additional $770 million improving its 225 narrow body planes in its fleet.
The airline will refit interiors and add new features on its Boeing 757-200 and 737-800 planes and the Airbus A319 and A320.
The investment is part of a $3 million multi-year program which began in 2010.
The program includes the installation of power outlets by every seat, in-seat video and satellite TV, new LED cabin lighting and updated lavatories.
Larger overhead bins will also be added, increasing carry-on capacity by an extra 50%, and gallies will be made more "space-efficient".
"We are continuing to make smart long-term investments in our products and services to meet the expectations of our customers," said Delta executive vice president Glen Hauenstein. "In just six years, we will have updated interiors throughout Delta’s fleet giving customers improved comfort and more options to work or relax and be entertained."
Additionally, in BusinessElite Delta will install flat-bed seating with direct-aisle access in its international wide body fleet by the middle of this year. It will be extended to all transcontinental aircraft in summer 2015.
Wi-Fi is already available on all domestic two-class aircraft and will now be rolled out across the international fleet by 2015.
