Daniel R. Bannister, 80, who as president and chief of executive of DynCorp from 1985 to 1997 led the government contracting firm through tremendous growth, died March 12 at Georgetown University Hospital. He had pancreatic cancer.

Mr. Bannister was paid $1.65 an hour when he joined DynCorp as an electronics technician in 1953. A half-century later, when DynCorp was sold to Computer Sciences Corp., Mr. Bannister had become the company’s chairman and one of its largest individual shareholders, owning 4.1 percent of the business.

During his tenure, Mr. Bannister oversaw the acquisition of more than 40 companies. When he retired in 2003, he was credited with helping to mold what had been an aviation services company into a sprawling conglomerate that employed 24,000 people and earned $2.4 billion in annual revenue.

Much of the company’s business stemmed from a variety of government contracts. Under Mr. Bannister’s stewardship, DynCorp employees mowed government lawns, maintained military aircraft and built federal computer networks.

He oversaw DynCorp contracts to operate missile test ranges for the Defense Department, develop vaccines for the National Institutes of Health and install security systems in U.S. embassies for the State Department.

As a private security contractor, DynCorp supplied bodyguards to Haitian President Jean-Bertrand Aristide in the 1990s and to Afghan President Hamid Karzai during the early 2000s.

In 1992, by highlighting his company’s technical advances on computerized operations, Mr. Bannister helped DynCorp win a lucrative contract to operate and manage the U.S. Strategic Petroleum Reserve.

Mr. Bannister, a longtime McLean resident, stepped down as DynCorp’s president and chief executive in 1997 to become chairman of the board.

Seven years after he left the company, DynCorp was sold to private-equity firm Cerberus Capital Management in 2010.

Daniel Richard Bannister was born June 29, 1930, in Detroit. When he was 11, his father died and Mr. Bannister was compelled to take a leading role in his family’s welfare.

He enlisted in the Air Force in 1948 and was trained as a radar technician. After service in the Korean War, Mr. Bannister left the military in 1952 and a year later joined Eastern Airways, a precursor of DynCorp.

DynCorp was a publicly traded company for many years until 1988, when Mr. Bannister led a group of investors to take the company private in order to fend off a hostile takeover attempt.

After the buyout, Mr. Bannister began to expand DynCorp’s interests in telecommunications and technology.

His marriages to Sheila Thompson and Paula DeCoutis ended in divorce.

Survivors include his wife of four years, Sondra Fearnsides Bannister of McLean, Va.; three children from his first marriage, Michael Bannister of Wimberley, Tex., Linda Epstein of Estero, Fla., and Vickie Pasterak of San Diego; a sister; and four grandchildren.

In 1996, Mr. Bannister was supposed to accompany Commerce Secretary Ronald H. Brown on a visit to Eastern Europe, where DynCorp had contracts to repair infrastructure destroyed during the Bosnian War.

Two days before the trip, Mr. Bannister decided not to go because of scheduling conflicts.

On April 3, the plane that he would have been on crashed into a mountain in Croatia, killing the commerce secretary and 34 others. When Mr. Bannister learned of the accident, he still had the trip’s itinerary in his suit pocket.

“I’m lucky, I’m grateful, and I’m humbled,” Mr. Bannister told The Washington Post in 1996. “The good Lord spared me for a purpose. Now, I’ve got to figure out what that purpose is.”

From that point forward, his family said, Mr. Bannister intensified his focus on philanthropy. He made significant contributions of his time and money to Easter Seals, Joe Gibbs’s Youth for Tomorrow and a number of other charities in the Washington area.