United Continental Holdings Inc.’s top communications executive is stepping down after leading the airline’s public-relations strategy through a tumultuous two-year tenure and worldwide scandal this April. Jim Olson, senior vice president of corporate communications, will resign effective Jan. 8 to pursue other opportunities, he said in a letter to employees. The decision was his own and he wasn’t asked to leave, Megan McCarthy, a United spokeswoman, said Thursday. The airline is searching for his replacement. Olson is leaving after a chaotic period that included a corporate turnaround effort, a battle with activist investors and a media firestorm when a passenger was dragged off a United Express flight in Chicago. When Olson arrived, United still was recovering from a scandal in which its chief executive officer was ousted for his role in flights scheduled to benefit a New York-area airport official. The new boss, current CEO Oscar Munoz, suffered a heart attack just a month after taking the job and underwent a heart transplant three months later. Soon after Munoz returned, the airline became embroiled in a proxy fight with two hedge funds, which ultimately redrew United’s board. This April, passenger David Dao was dragged from a plane by Chicago airport officials after he refused to give up his seat to make room for a crew member. United’s initial comments, such as Munoz’s apology for having to “re-accommodate” the passenger, sparked worldwide condemnation in the press and on social media. United absorbed another blow on Oct. 19, when it reported earnings. The shares dropped the most in eight years after Munoz and President Scott Kirby couldn’t answer analysts’ questions about United’s growth and cost projections for next year. Olson joined United from Starbucks Corp. and earlier worked in communications for US Airways and Nissan North America. While at US Airways, he managed the airline’s response to Flight 1549, which landed on the Hudson River off Manhattan in 2009, according to United’s website. United has been stuck behind Delta Air Lines Inc. and American Airlines Group Inc. in terms of profit margin. Its stock is down 13 percent this year, compared with a 6.5 percent gain for a Standard & Poor’s index of major U.S. carriers.