Raymond N. Plank, a coal miner’s son and former combat pilot who witnessed the atomic-bomb attack on Nagasaki and then returned from the war to help found one of the nation’s largest independent oil and gas companies, Apache, died on Thursday November 8 2018 at his home in Ucross, Wyo. He was 96. His death was confirmed by his son Roger. home in Minneapolis after his service and armed with a degree from Yale, he saw a postwar surge in small businesses on the horizon. And those businesses, he knew, would need accounting and tax services. He and two business partners rented a tiny third-floor walk-up apartment in Minneapolis. They called Northwest Business Service, was selling insurance, mutual funds and, most auspiciously, interests in drilling oil wells. Mr. Plank and his partners, in 1954, formed the Apache Corporation, which was originally set up to raise investor funds for oil and gas drilling. It ultimately expanded into exploration and production itself, becoming one of the nation’s largest independent oil and gas companies, with reported revenue of almost $6 billion in 2017. Mr. Plank pioneered the use of what came to be known as master limited partnerships, or M.L.P.s, an investment vehicle that can be traded publicly and offer significant tax advantages to investors. But when oil prices fell in the 1980s and tax laws made public drilling programs less appealing, Apache dropped the partnerships. Apache then moved to Denver with a plan to transform itself into a company that owned and operated oil properties for its own account. After doubling its assets and balancing its oil and gas holdings through deals with Amoco, Shell and British Petroleum, the company began to exploit a large concession in Egypt. Mr. Plank retired from Apache in 2009. Raymond Norwood Plank was born on May 29, 1922, in Wayzata, Minn., a small city on the shore of Lake Minnetonka, about 13 miles west of Minneapolis. His coal miner father, Raby, was also a farmer; his mother, Maude (Howe) Plank, was a homemaker. Raymond grew up on a farm, and his mother died when he was a teenager. In addition to his son Roger, Mr. Plank is survived by three other sons, Michael, Raby and Dana; two daughters, Kate Plank Sage and Pamela Plank Thaut; 12 grandchildren; and 11 great-grandchildren. His marriages to Sally Bovey Stevens, Lollie Benz and Heather Burgess ended in divorce. Mr. Plank’s philanthropy was wide-ranging. In addition to establish the nonprofit Springboard — Educating the Future to build girls’ schools in Egypt, he created the Ucross Foundation in northeastern Wyoming in 1981 and set up a conference center on a 20,000-acre working ranch there. RAYMOND PLANK has been chairman of the Company's board of directors since 1979, having served as the company's chief executive officer from 1966 until May 2002, and president from 1954 to 1979. Mr. Plank is a trustee of Ucross Foundation, a Wyoming non-profit corporation, and founder and a director of The Fund for Teachers, a Texas non-profit corporation. He founded the Company and is a member of the Executive Committee.