Question: The company, in which Warren Bradford Rigdon was a former business executive for, merged with Boeing in what year?

Context articles: James G. Ellis
Bruce Barnes (executive)
Business routes of U.S. Route 23 in Michigan
Peter A. Appel
James Ting
Raymond Gilmartin
W. Bradford Rigdon
Rusty Schweickart
McDonnell Douglas
Lloyd Levitin

James George Ellis (born 9 Jan 1947 Tacoma, Washington) is an American academician, professor, and former business executive who, for the last years, has been dean of the Marshall School of Business at the University of Southern California in Los Angeles, California.
Bruce Barnes (born March 15, 1962 in Los Angeles) is the eighth director of the George Eastman Museum, founder of Leeds Art Foundation, and a former business executive, investment banker and investment fund executive.
There have been five different business routes of US Highway 23 in the state of Michigan.
 These business routes were designated along former sections of US Highway 23 (US 23) to provide signed access from the main highway to the downtowns of cities bypassed by new routings of US 23.
 Two are still extant, connecting through downtown Ann Arbor and Rogers City.
 Three others have been decommissioned.
 The former Business US 23 (Bus.
 US 23) in Fenton was split in half during the 1970s and later completely turned back to local control in 2006.
 The former business loops through Saginaw and Bay City were renumbered as business loops of Interstate 75 in the 1960s.
Peter A. Appel (born 1962) is an American entrepreneur, investor and former business executive.
 Appel, a Founder and former President and Chief Executive Officer of Arch Capital Group Ltd., is currently the Non-Executive Chairman of Aeolus Capital Management LLC, an asset management firm he founded in 2011 and oversaw as Chairman and CEO until it was sold to Elliott Management in January 2017.
James Henry Ting Wei (丁謂, born 1951) is a Shanghai-born Chinese-Canadian former business executive who was once one of Hong Kong's most successful businessmen before being caught of illegal business practices.
Raymond V. Gilmartin (born March 6, 1941) is an American former business executive and an Adjunct Professor of Management Practice at the Harvard Business School.
Warren Bradford "Brad" Rigdon (born 1939) is an American engineer and former business executive at McDonnell Douglas, also known for developing the NIST Enterprise Architecture Model.
Russell Louis "Rusty" Schweickart (also Schweikart; born October 25, 1935) is an American aeronautical engineer, and a former NASA astronaut, research scientist, U.S. Air Force fighter pilot, as well as a former business executive and government executive.
McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967.
 Between then and its own merger with Boeing in 1997, it produced a number of well-known commercial and military aircraft such as the DC-10 airliner and F-15 Eagle air-superiority fighter.
Professor Lloyd A. Levitin (born 1932) is an American businessman, former business executive, and currently professor of clinical finance and business economics at the University of Southern California's Marshall School of Business.
 He teaches financial analysis and valuation courses in the full-time MBA and undergraduate programs.
 He has published articles on corporate diversification and accountants' scope of liability for defective financial reports.
 He was simultaneously executive vice president, treasurer and chief financial officer of Pacific Enterprises (now Sempra Energy), as well as executive vice president and chief financial officer of the Southern California Gas Company (wholly owned subsidiary of Pacific Enterprises).
 He has 31 years of experience in corporate management.
 Prior thereto, he was associate professor of business at San Francisco State University.
 He also has a CPA certificate.