'Jetpack man' reported flying close to planes at Los Angeles Airport

As air traffic in the United States increases, it was probably just a matter of time before 'the jet pack guy' made another appearance in the skies above Los Angeles.

On Thursday night local time, after an absence of about a year, the unidentified flying object which pilots have described as looking like a man with a jetpack was spotted somewhere he shouldn't be.

The pilot of Skywest flight 3626 was on final approach to Los Angeles International Airport when air traffic controllers gave him a warning.

"The jet man is back."

The Federal Aviation Administration (FAA) confirmed the incident in a statement and said investigations into what had happened and who was responsible were ongoing.

"A Boeing 747 pilot reported seeing an object that might have resembled a jetpack 15 miles east of LAX at 5000 feet altitude," a spokesperson said.

Out of an "abundance of caution", air traffic controllers alerted other pilots in the vicinity.

"Skywest 3626, use caution. The jet man is back, let me know if you see him," an air traffic controller told pilots.

"Skywest 3626, did you see the UFO?" The controllers then asked.

"We were looking, but we did not see Iron Man," the pilot replied.

The jet pack man was last seen 10 months ago in almost exactly the same spot. An investigation by the FBI was unable to identify the object or the person responsible.

David Mayman, the CEO of Los Angeles based Jetpack Aviation, told CBS News there was no technology available that could do what the jetpack man appears to be doing.

"They'd run out of fuel, they use fuel too quickly," Mayman said.

He said most jetpacks can only fly for five to 10 minutes.

"If it's a real jetpack, it's noisy. People would have heard it take off and land."

One theory is that the object is in fact a drone with a jetpack costume attached to it.

Audio of the spotting can be heard in the video above.