The deaths of apartment executives Steven and Daniel Altman in a midair plane-helicopter collision above the Hudson River between Manhattan and Hoboken, N.J., have left family members and associates devastated.

The brothers, both prominent Philadelphia area businessmen, and Daniel Altman's son, Doug, 16, were killed Aug. 8. when Steven Altman's single-engine Piper plane and a sightseeing helicopter carrying five Italian tourists and a pilot collided. All nine occupants of both aircraft died.

Steven Altman, 60, and Daniel, 49, were principals of the Altman Group, a 50-year-old Pennsylvania apartment company founded by their father, David Altman, now 87. Altman Management Co., which Steven Altman headed, operates 14,000 apartment units and owns about half of them.

The former president of the Apartment Association of Greater Philadelphia, Steven Altman flew to the state capital, Harrisburg this year to advocate for new industry legislation, says board member Larry Falkow.

“They were iconic figures. If there was a Mount Rushmore of apartment owners in this region, they would be up there,” says Falkow. “It's a huge loss. It leaves a void that can't be filled.”

Based in Fort Washington, Pa., the Altman Group has earned many awards, says Falkow.

Steven Altman flew humanitarian missions for Angel Flight East, transporting medical patients to hospitals at no charge. A relative, Joel Altman, 66, chairman of the Altman Cos., a separate multifamily development firm based in Boca Raton, Fla., says Steven followed the example of his father, a pilot and World War II hero who survived the battle of Iwo Jima.

Joel Altman partnered with Steven in a seniors housing development in Detroit. “Steven is younger than I, but I always had the utmost respect for Steven. He was very bright, a real thinker. I'm deeply saddened. I've always thought the world of Steven and Daniel.”

A surviving, brother, Brett, works on the construction side of the business.

The Altman brothers had a good sense of humor, says Falkow. “They were just great guys, the kind of guys you want to hang out with and pal around with.”

With strong management in place, the Altman Group will continue for now, industry sources say.

Joe Mullen, president and CEO of the Philadelphia-based Madison Apartment Group, one of the country's largest apartment owners, knew Daniel Altman. “Dan was a real gentleman who did a great job,” says Mullen. The two occasionally played golf and compared notes on the economy. “We'd talk about what we're seeing in our industry, how we're buying properties, how we're running them.”

The Altmans have a great organization, and they were strong advocates for the apartment market, says Mullen. For the families and the industry, the crash is “horrible,” a terrible loss.

“You're going to miss a voice in our industry. There's no question of that,” adds Mullen. “It's a sin. An absolute tragedy.”