Chicago ? United Airlines mechanics and aircraft cleaners approved a contract Tuesday that will give them their first raise since 1994 and end a bitter two-year dispute.

The contract was ratified by 59 percent of the voting membership, union officials said.

The approval averted a strike that could have started as soon as 11:01 p.m. CST today. Analysts have said a walkout would have grounded the airline and forced it into bankruptcy.

The ratification removes a key obstacle for the struggling carrier as it pursues a recovery plan aimed at stemming its financial hemorrhaging. The Elk Grove Village, Ill.-based airline lost an industry-record $2.1 billion last year and its troubles have continued the carrier said Tuesday that passenger traffic in February fell 13.8 percent from a year ago.

The 12,800 mechanics and cleaners resoundingly rejected a previous contract offer three weeks ago and authorized a strike. But United sweetened the terms of the five-year pact and negotiators reached a tentative agreement Feb. 18.

Under the new contract, senior mechanics’ pay would go from $25.60 an hour to $35.14, or about $73,000 a year. For top-scale aircraft cleaners, hourly pay would increase 19 percent to $19.76 an hour, or about $41,000 a year.

Those figures were unchanged from the previous offer. But United made other key changes in order to win the approval of negotiators from District 141-M of the International Association of Machinists and Aerospace Workers, including increasing the retroactive pay due each mechanic to $16,500 from $12,500, speeding the timetable under which it will be paid, and boosting pensions