(FORTUNE Magazine) – THE NEW MARTIN SCORSESE EPIC, The Aviator, portrays Howard Hughes, played by Leonardo DiCaprio, as an eccentric genius. Beating the world record of fastest flight around the globe and buying TWA (ultimately preventing PamAm from gaining exclusive rights to fly overseas) are but two of his dashing onscreen feats.

But what was Hughes like as a businessman? Curious about his offscreen acumen, FORTUNE tracked down one of his last living colleagues--Dr. Simon Ramo. "Hughes was no genius when it came to business or technology," says Ramo, now age 91, from his office in Beverly Hills. In 1946 Ramo was a young researcher at GE when he decided to join Hughes Aircraft, then Howard Hughes's airplane workshop, to launch a division devoted to high-tech defense electronics.

To hear Ramo tell it, Hughes was a mostly absentee boss who cut a bizarre figure around the office (Ramo's 1988 book, The Business of Science, which FORTUNE excerpted that year, includes a chapter on Hughes). Ramo recalls that Hughes's detailed directives included instructions about what kind of seat covers to buy for the company's fleet of Chevrolets. Hughes also suggested the company build a missile testing range on his Nevada property, ignoring the fact that only the government can test guided missiles. Science, says Ramo, simply wasn't Hughes's priority. "It's hard to be smart about the defense business if you don't even understand how a gyroscope works," he says.

Ramo eventually parted ways with Hughes in 1953. The Defense Department had grown wary of sending so much business to the eccentric billionaire (Hughes Aircraft had grown into a multimillion-dollar defense-electronics business and a top supplier of guided missiles), and Ramo and an associate decided to start a rival firm. Hughes, who was living in Las Vegas and at this point subsisting only on milk, was desperate to keep Ramo, begging the young engineer to visit him in Vegas, where he told him that "everyone has a price."

Ramo left, and went on to found defense contractor Ramo-Wooldridge in 1953 (it became TRW), then in 1964 he started Bunker-Ramo (now part of Honeywell). Ramo never saw Hughes again, though they spoke several times when Hughes sought business advice. (Hughes Aircraft survived until 1985, when it was bought by GM; the renamed Hughes Electronics was then sold to Raytheon in 1997.)

About a year ago Ramo was approached by Aviator producers, but he turned down a lunch with Martin Scorsese and DiCaprio, instead urging them to read the chapter in his book. "I'm not going to go to lunch just because I think it would be so great to have lunch with that fellow from the movie about the ship going down," says Ramo. Asked whether he'll see the movie about his old boss, Ramo replied: "At age 91½ I don't really go to movies; you have to park and wait in line. I think I'll just wait until I can see it on TV." -- Julia Boorstin