Pilots declare mayday after frozen fluids in nose of plane disrupt flight

The plane tried and failed twice to circle back to its departure point

An S7 aircraft in Russia (Getty Images)

Pilots were forced to call mayday, the signal for a life-threatening emergency, as they climbed out of Magadan, Russia on Wednesday.

S7 flight 5220 was en route to Novosibirsk when it encountered ice-related problems and took a sudden plunge shortly after take off.

“Following take off the aircraft flew into clouds and into a zone of severe turbulence accompanied by strong icing. As result the aircraft got into a difficult spatial position,” reads a report from the Air Accident Investigations Bureau.

The Airbus A321 twice tried to return to Magadan’s airport but pilots were not able to offload enough fuel to do so - forcing them to fly on for nearly five hours to a diversion point.

Eventually pilots were able to land safely in Irkutsk, down near the Mongolian border.

On landing, ice was found on the wings, as well as “frozen fluids” in the nose of the aircraft which had interfered with the plane’s sensors.

According to the AAIB report, “continuous snow fall and melting during taxi in ambient temperatures below freezing [had] caused a layer of frozen ice at the front part of the fuselage disrupting the airflow of the pitot tubes.

“Therefore, takeoff with the fuselage surface and engine hoods covered with a thick layer of snow in icing and turbulence conditions posed a real danger to the flight safety.”

Local police are reportedly investigating whether intentionally faulty or tampered-with de-icer was used on the aircraft fuselage before take off, , according to aviation blog View from the Wing.

De-icing is an important part of flight prep in cold countries, with special de-icing fluid made of a heated combination of chemical glycol and water sprayed on parts of the aircraft to stop them from freezing or failing on take off.

Ryanair and staff at Brindisi Airport were criticised in January 2019 after an aircraft at the southern Italian airport was filmed being de-iced using buckets of water rather than the approved chemical.