Delta Air Lines Inc. said Wednesday it will raise pay for flight attendants and ground workers by 14.5 percent in December and increase matches of employee contributions to retirement accounts.

The airline also will change the profit-sharing formula in a way that could boost payouts after lean years but might reduce them after highly profitable years such as 2014.

The International Association of Machinists and Aerospace Workers, which is trying organize Delta flight attendants, said raises were overdue and left Delta employees below industry-leading pay.

Only 18 percent of Delta workers, mostly pilots, are represented by unions. That is easily the lowest percentage among the leading U.S. airlines.

CEO Richard Anderson and President Ed Bastian said in a memo to employees that Delta was “providing you with record pay raises in a year of record profits.”

Last year, Atlanta-based Delta earned $4.5 billion in adjusted pretax profit, which excludes unusual costs and gains.

Currently Delta shares 10 percent of the first $2.5 billion in annual adjusted pre-tax profit with employees and shares 20 percent of profit above that. Starting with payouts in 2017, the formula will change — the 20 percent payout will start when pre-tax profit tops the previous year’s amount.

Delta also said that it will increase the cap on matching employee 401(k) contributions from 5 percent of pay to 6 percent.

Photo Credit: A Delta plane in Salt Lake City. Aero Icarus / Flickr