An airplane passenger took flying saucer speculation to new heights when she spotted a possible UFO soaring above the Big Apple — baffling experts and sending federal aviation officials on a fact-finding mission Thursday.

Michelle Reyes was on a commercial airline flight above LaGuardia Airport on March 25 when she captured video footage of a mysterious “flying cylinder” out of her plane window, she said on Facebook.

“The first thing I did was email the FAA to let them know what I saw,” she told NewsNation Wednesday.

“Maybe it was a safety hazard, but unfortunately I haven’t heard back from them, they didn’t acknowledge my email.”

She said another person on the flight saw the out-of-this-world object and was stunned.

“It’s a little nerve-wracking that someone else saw what I saw,” she said.

Thomas Wertman, the state director of the Mutual UFO Network in Ohio, reviewed the footage for The Post and said the dark object was traveling at roughly 2,500 feet and was “relatively close” to the plane as it prepared for landing.

The object’s altitude, shape and location — near a major commercial flight path — appears to rule out that it could be a news helicopter, a drone or a military-operated aircraft, Wertman said.

“Drones aren’t supposed to fly at that altitude at least legally,” he said.  “If it were something related to [military] defense or law enforcement,  you normally wouldn’t see it so close to a major flight lane.”

“That could be a potential hazard,” said Wertman, who has spent years studying the skies for evidence of interplanetary visitors.

The unusual round shape of the object struck him as “intriguing”  because it debunks the theory that it was a second plane filmed at an odd angle.

“It does not appear to be a commercial aircraft because I don’t see features like wings or a tail,” he said.

The plane Reyes was aboard was roughly 15 minutes away from LaGuardia Airport likely traveling 230 mph when the video was shot, he said.

Ultimately, the footage “doesn’t appear to be doctored,” he said.

“It’s a very intriguing image,” he said. “It needs more research.”

There are other theories he can’t rule out, such as high-flying wildlife and weather balloons, without metadata from the footage and other information.

Metadata would help him glean clues about the direction the plane was flying and the exact time of the sighting.

A Federal Aviation Administration official said Thursday the agency has “no reports” from pilots about the mysterious incident.

The flight number and time were not clear Thursday.

Reyes didn’t immediately return a request for comment.