While flying the Mercy Air 21 helicopter on Sunday, the pilot detailed how the unidentified object was hovering some distance away from his position.
However, the object was only visible through his night vision goggles.
During the radio exchange between the pilot and an air traffic controller, the man shared the bizarre sighting while flying over Las Vegas, Nevada, US.
He said: “Just to advise, it looks like I have some sort of object over the southern hills area looks to be about 7,000ft, could be a balloon or something along those lines.
“It’s unlit so just advise.”
The radio controller replied: “Okay, I’m not seeing anything in that area but that’s not to say there’s something not out there.”
“I can only see it, I’ve got night vision goggles on, I can only see through the goggles,” the pilot replied.
The seemingly amazed controller answered: “Ooh, that’s awesome.”
There were no details provided in order for a further investigation to go ahead.
Mercy Air operations base – where the helicopter flew out of – told Air Methods headquarters not to provide comment or allow access to the pilot who was talking on the radio, The Drive reported.
YouTube conspiracy channel Secureteam10 uploaded the video yesterday, proving popular after gaining some 84,000 views.
One person claimed: “More and more people are coming out and putting their jobs on the line.
“We might be getting somewhere.”
Another added: “Las Vegas is around the Area 51 so I think its a UFO/Aliens.”
“It was invisible camouflage they are way smarter than us but not smart enough for night vision.” a third claimed.
The sighting remains a mystery.
Last month, a pilot flying over Gloucester discovered “peculiar lights” hovering over the town, released radio transmission recordings have revealed.
It’s not the first time a UFO has been spotted in the sky above the US.
Last week, a “guardian angel” was spotted hovering over New York, sending conspiracists into a frenzy.
Astronomers are searching for “extraterrestrial civilisations” starships inside of black holes on space, it has been revealed.