At an age when most little old ladies are happy if they can lace up their tennis shoes, 84-year-old Marion Hart doesn't consider it much of a day unless she has flown solo across the Atlantic. The Amelia Earhart of the geriatric set ("Don't call me a flying granny. I'm divorced and childless"), she has negotiated the U.S.-to-Ireland hop six to eight times—she concedes airily that she's lost actual count—and that's only the beginning. She has been zipping around the world to exotic places (Dacca, Agadir, Abidjan, Singapore, the Sahara) ever since she got her pilot's license at the age of 55.

A New Yorker then, she decided one day in 1945 that she wanted to fly, picked Teterboro, N.J. Airport out of a telephone book, and soloed after 10 hours of instruction. Now, some 5,000 flying hours later, Mrs. Hart is off on a 10-month globe-trot in her single-engine 1961 Beechcraft Bonanza. Her luggage: two washable dresses, two pair of moccasins, a pair of rain shoes, two cameras and some books. "I'm going to be away," she says, "until the weather is nice back home."

Her spunk showed early. The fourth of six children born to wealthy New York lawyer-businessman Isaac L. Rice (who built the first modern submarines), young Marion graduated from MIT in 1914 as the first woman in the U.S. to win a degree in chemical engineering. She took a master's in geology at Columbia, went "around the country knocking off bits of rock—a grand occupation" and married another geologist in 1918.

The union lasted "seven or eight years," she recalls. "It was just after the war and everyone seemed to be getting married. I knew him for two weeks. He never could understand about the things I wanted to do and why I didn't do things everybody else did. It was an experience, but not a very interesting one."

For some years afterward, Mrs. Hart lived the rich life at her mother's New York apartment, their New Jersey estate and a French home near Avignon. She studied sculpture and in 1936 embarked on a three-year round-the-world cruise in her own six-crewman ketch. She fired four captains, took the helm herself, and eventually wrote a book on navigation that went through five editions. Mrs. Hart's first transatlantic flight (with another pilot) came in 1953 and her first solo crossing in 1966. "I was a bit nervous on that trip," she recalls. "I went out about 50 miles before I remembered to take the flaps up."

Whatever mystique flying exerts for romantics, it holds little for her. She hoots at the vaporings of Jonathan Livingston Seagull. "I am not very sentimental about flying," she says. "I never had exalted feelings. I don't even call it a feat as long as the engine keeps going."

She also flies unburdened by such standard equipment as radar, a dinghy or oxygen. "I stay at 9,000 feet," she says. "You don't need oxygen there." She scorns food, too. A roll of peppermint Life Savers and a bottle of water is enough, even on Atlantic runs.

She is fatalistic about engine failure, but does fret about her radio going out. Once, near Greenland, her long-range radio went and her compass developed a leak. Luckily, a nearby pilot was able to guide her into an airport. Another time, en route from Kabul, Afghanistan to R?walpindi, Pakistan, her radio failed and she landed an hour late. "They were very suspicious," she recalls. "In that part of the world, they always think I work for the CIA. On the radio they always ask, 'Where is your captain?' I say, 'I am the pilot.' They say, 'Can you fly solo?' I say, 'What does that mean?' Then they leave me alone."

A small woman with bright blue eyes and a stylish blond wig, Mrs. Hart's only problem stems from old cataract operations, now largely corrected by contact lenses and glasses. "Without them," she admits, "I see two runways when I come in." (She has a third-class pilot's license which requires a physical exam every two years.)

Mrs. Hart's home base now is an apartment across the street from the Watergate in Washington. But she doesn't linger very long. "I just close up my apartment, leave a check for the landlord, and go. Money. That's the secret of my success."