An old cowhand from Madison Avenue, Michael Kammerer made a fortune selling television advertising, retired early, and galloped into the sunset in pursuit of projects as diverse as competitive cattle roping and bankrolling expeditions to find the remains of Amelia Earhart.

Kammerer, who died at 67 on May 12 in Albuquerque, N.M., was founder of the Independent Television Network, now ITN Networks, a New York company that pioneered what the industry calls “unwired networks.” Unrelated to the Internet, the idea was to buy from independent television blocks of advertising time that could then be broken up and sold as individual ads to sponsors seeking specific viewer demographics.

Kammerer, a Long Island native who had spent two decades in the advertising business, became one of the first to test the concept when he founded ITN in 1983. Profits were elusive for the first few years, but then big-time advertisers joined in, including Ford Motors, American Home Products (now Wyeth), and Hanes. Kammerer retired from managing the business in 1991 and moved to Santa Fe, N.M., where he lived in a 20,000-square-foot adobe mansion on 174 acres of high desert.

He had embraced the cowboy life years before, having moved from his Chappaqua home to an upstate New York ranch, where he ran a beef cattle operation even as he pursued advertising. In Santa Fe, he pursued team roping and treasured the United States Team Roping Finals Reserve belt buckle he won in 1998.

How Kammerer became interested in Earhart is unknown, but in 2001 he spent nearly $1 million to purchase a 1935 Lockheed Electra 10-E, one of the only models of the plane Earhart used in her attempt to circumnavigate the globe in 1937. She disappeared somewhere over the South Pacific during that flight, and discovering what became of her has been a cottage industry ever since. The Electra 10-E was used by pilot Linda Finch in a successful circumnavigation along Earhart’s route, in 1997.

In 2001, Kammerer heard about a planned expedition to the South Seas in search of Earhart by a group of archaeologists and crash site specialists calling themselves the International Group for Historic Aircraft Recovery. In exchange for $300,000, which bankrolled a season of excavations, Kammerer won the commercial rights to the fruits of the search.

“He wanted to have them shoot an episode of ‘Survivor’ on the island while we excavated,” the executive director of Tighar, Ric Gillespie, said. He called Kammerer “a loose cannon on a rolling deck.”

In the event, nothing definitive was found — only some rusty trinkets — and Kammerer moved on to a new hypothesis: that Earhart’s wrecked plane was beneath the sea. He then bankrolled a new expedition with a small submersible called Argus. That expedition never materialized.

Kammerer also founded one of New Mexico’s larger foundations, the Code of the West Foundation, to honor people who perform heroic deeds or keep their word.

He is survived by a son, a daughter, and his second wife, Susan Bodelson Kammerer.