Air traffic control issued a squawk alert 7700 which indicates a general but unspecified emergency. The plane began circling over London airspace for nearly an hour, according to flight radars.
Ryanair has confirmed that Lauda Europe flight LW888 encountered a “technical problem” and was forced to return to the airport.
The airline added that it was a non-passenger plane.
The Airbus A320 was scheduled to take off from Stansted at 8.45 a.m., but took off 30 minutes later, according to Flight Radar 24.
The plane took off at 9:15 a.m. and was in the air for 52 minutes.
He landed at Stansted at 10:07 am sharp.
“In accordance with procedures, the captain requested a priority landing at Stansted, where the aircraft landed safely at approx. 10:07 am local time.
A Stansted Airport spokeswoman added: ‘It was a training flight with no passengers on board who returned to Stansted as a precaution.
“The plane landed safely.”
A squawk code is a four-digit code used to facilitate rapid communication between air traffic control and the aircraft.
A 7700 squawk the code is used to communicate all emergencies on board a flight and sends an immediate alert to all nearby watchtowers.
Other notable codes include a squawk 7600, which is used to inform Air Traffic control the plane lost communications with the towingr.
A The squawk alert 7500 is used in a hijacking and informs the tower that the aircraft needs emergency support from security services.