Weird vertical flame startles uptown Charlotte office workers. Here’s the source.

Uptown Charlotte office-tower workers and high-rise apartment dwellers spotted a mysterious “vertical” flame shooting skyward Friday as they stared out their windows slightly to the southwest. Drivers snapped photos and shot video.

But no need to call the fire department if you spot the flame or hear a hiss or a boom this week.

The flame is from a “flare stack,” or large vertical pipe that also can produce a whistling sound and a smell of natural gas, according to a Piedmont Natural Gas Co. news release.

The flare stack is in the 800 block of Spruce Street, just east of Interstate 77 and Wilkinson Boulevard, and is part of routine pipeline maintenance in that area that will continue through Thursday, officials said.

Piedmont Natural Gas employees are managing the “controlled flare stack operation” in cooperation with the Charlotte Fire Department, company officials said.

“Piedmont’s No. 1 priority is safety – for its customers, its employees and the communities it serves,” according to the release. “These activities are key to continuing Piedmont’s safe, reliable natural gas service and meeting the increased demand for natural gas.”

The company issued a news release Wednesday, but even some of its workers called in about the flame, spokeswoman Tammie McGee told The Charlotte Observer on Friday. She didn’t know how many people have called the company’s customer support line about the flame.

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Joe Marusak has been a reporter for The Charlotte Observer since 1989 covering the people, municipalities and major news events of the region, and was a news bureau editor for the paper. He currently reports on breaking news.