The flying range of jet packs is pretty limited, Anthony added, so it's unlikely it traveled any great distance.
After the China Airlines pilot's report Wednesday, the LAX control tower called in a law enforcement aircraft to investigate.
The aircraft was flying about seven miles from where the pilot said he'd seen the jetpack, according to radio communications.
But when the craft arrived, no signs of the jet pack remained.
A jet pack could be operated as an ultralight - meaning it would not be registered and its operator wouldn't need a pilot's license if it meets fuel capacity, weight and speed requirements, according to the FAA. Ultralight aircraft are permitted to fly only during the day and are barred from flying over densely populated areas or in controlled aerospace without FAA approval.
Anthony and others say it's imperative that the FBI investigate the sightings for safety.
"This does represent a very significant compromise of the airspace," he said.
If a rogue pilot were flying at 6,000 feet without a transponder or radio, Anthony said, that would put him or her in the path of commercial airlines maneuvering over Los Angeles.
Airliners are designed to withstand getting hit by small objects. But a big metal object is another matter, especially if it were sucked into an engine.
"The engines aren't designed to consume something large and metal, or something with fuel that's going to burn or explode," Hirschberg said. "That could be potentially catastrophic for an airplane. You could potentially have an engine explode and bring down the airliner and potentially hundreds of people could die."