An air traffic controller has been restricted from controlling air traffic amid an investigation of an incident that caused a Delta plane to circle around the Atlanta airport.

The Federal Aviation Administration is investigating what some reports have characterized as a joke by the air traffic controller.

Last Wednesday afternoon, Delta Air Lines flight 630 from Detroit came in for a landing at Hartsfield-Jackson International Airport when, with the Boeing 777 about 1,000 feet off the ground, a controller told the pilot to execute a “go-around” procedure.

The pilot was then quickly told to cancel the procedure and was re-cleared to land, according to the FAA. But the missed approach was already in progress.

According to a brief portion of a transcript of the conversation reported by Channel 2 Action News, the pilot had told the controller there was no available gate for the flight and suggested the controller determine a parking spot until one came open. The controller replied “Delta 630 go around,” then a few moments later added, “I’m kidding, Delta 630” and indicated he would find a place for the plane on the ground. “Delta 630 … you’re cleared to land.”

The pilot responded that he had already initiated a missed approach and was “on the go.”

The controller’s phrase “I’m kidding” prompted news reports that the controller was playing a joke of some sort, but the FAA offered no theory as to why the controller issued the initial go-around order and then immediately changed it.

Go-arounds are not uncommon and can be triggered by a variety of factors, ranging from weather to taxiing planes being too close to the runway being used.

The Delta jet climbed back to about 4,000 feet, circled the airport once and landed less than 15 minutes later on its second approach, according to flight-tracking website Flightradar24.

Delta said no customer concerns were reported “and the flight landed without incident,” according to Delta spokesman Morgan Durrant.

The airline said it will fully cooperate with the FAA on the matter.