United Airlines Flight 155 made an emergency landing at the A.B. Won Pat International Airport on Monday morning.
Airport Marketing Administrator Rolenda Lujan Faasuamalie said the flight left Guam at 8:12 a.m.
A little more than an hour into the flight, at 9:26 a.m., the pilot told passengers that the plane's stall indicator light had come on and the flight would be returning to Guam.
Faasuamalie said the airport agency initiated an Alert 2, which means Aircraft Rescue and Firefighting services were placed on standby for an emergency landing.
The flight, which used a Boeing 737, landed safely at 10:06 a.m.
"It was a very smooth landing and there were no injuries," she said.
A release from United Corporate Communications said, "As a precaution, the crew declared an emergency."
The statement described the problem as "a mechanical issue" and said the "maintenance team is currently inspecting the aircraft."
United will operate a special flight this morning to accommodate the passengers.
"We apologize to our customers for the inconvenience caused. The safety of our customers and employees is our top priority," the release states.
Not a Boeing 737 Max
The aircraft, while a Boeing 737, isn't part of the Boeing 737 Max fleet of planes that the Federal Aviation Administration temporarily grounded in March. The FAA stopped U.S. airlines from flying Boeing 737 Max aircraft following the crash of Ethiopian Airlines Flight 302.
Faasuamalie said no airline flying into Guam or operating flights from Guam used Boeing 737 Max aircraft, even before the grounding.
Flight 155 is not the "island hopper" flight that starts in the U.S. mainland and hops from one Micronesian island to another including a Guam stop. It is a direct flight to Chuuk followed by a return to Guam.