A United Airlines flight bound for Chicago was forced to make an emergency landing in Miami shortly after midnight following a mechanical failure mid-climb.
MIAMI — United Airlines Flight UA3877, a scheduled service from Miami International Airport (MIA) to Chicago O’Hare International Airport (ORD), was already running more than an hour and 20 minutes behind schedule when it finally took off from runway 8L. However, the flight’s troubles were only just beginning.
Flight Aborted Mid-Climb
According to flight tracking data, the aircraft (a 27-year-old Boeing 737-800, registration N12216)abruptly halted its ascent at just 6,850 feet. The flight crew reported a mechanical issue and immediately contacted Air Traffic Control (ATC) to request an urgent return to Miami.
While on approach back to the airport, the pilots escalated the situation by transmitting a “Squawk 7700” code, the international radio signal used to declare an in-flight emergency. The declaration ensured the flight received priority handling from air traffic controllers as it lined up for landing.
Safe Touchdown and Major Delays
The aircraft landed safely on MIA’s runway 9 approximately 50 minutes after its initial takeoff. Emergency services were on standby, but the plane was able to taxi back to the terminal under its own power, allowing passengers to deplane normally.
United Airlines later confirmed that the turnaround was prompted by a maintenance issue.
“United flight 3877 returned to Miami safely following a maintenance issue shortly after takeoff. We apologize to our customers for the inconvenience,” the airline said in a statement.
A replacement aircraft was brought in to resume the flight, which is ultimately rescheduled to depart five hours behind its original time.

