Brendan Hill said he was always jealous of his brother’s drive, and Mr. Hill’s short career showed a young man with wide interests and varied talents. He worked at the Sierra Nevada Corporation for a time, and briefly co-owned a bar in Reno called the Stamp Social Club, which was in the basement of an old 1930s post office. He even interned on Capitol Hill for Representative Michael R. Turner, a Republican from Ohio.

In a statement on Monday, Mr. Turner said: “Tristan’s personality, intellect, and constant smile were always on display when he worked with us. I was deeply saddened to learn of his passing and my prayers go out to his family. The joy and happiness that he brought to all of us will not be forgotten.”

But it was Mr. Hill’s latest venture, his younger brother said, that brought him into the tourist helicopter. He moved to New York a few months ago to work on a sightseeing website called SightSy, where he was the director of operations. One of the activities listed on SightSy is the “Manhattan Sky Tour: New York Helicopter Flight.”

Mr. Hill’s other brother, Iain Hill, wrote a tribute to him on Facebook.

“The world lost a legend last night,” he wrote. “Few have brought so many together. It is in that vein I post, to help let those people know … It never mattered the schedule, if there was an experience to be lived, or more important a friend in need, he rose to the occasion.”

Image Tristan Hill

Ms. Vallejos Blanco arrived in New York from Argentina on Wednesday and was planning to stay for a week, said Mateo Estremé, the consul general of Argentina in New York. Roxana Blanco, Ms. Vallejos Blanco’s aunt, told Pulxo, an Argentine radio station, that her niece’s traveling companion decided she would rather skip the Sunday evening ride.

“Carlita liked to take pictures and wanted to take pictures from the helicopter, and her friend wanted to do something else,” Ms. Blanco said. “So they agreed to meet at a certain spot later.”