On January 16th, an aircraft swap led to a Wizz Air Flight from London Luton to Prague taking off outside of its center of gravity limit. Fortunately, the plane landed safely at its destination. Following the incident, Wizz said it would improve information procedures and provide additional training for cabin crew on the implications of weight and balance.
According to the incident report seen by Simple Flying, Wizz had initially scheduled the departure with an A320, seating 180 passengers. However, on the day there was a change to an A321 aircraft, which has a larger passenger capacity, with 230 seats.
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Information never reached Luton
Due to a technical error, an automated email from Wizz’s control center announcing the change did not reach the Operational Handling Department (OHD) and Passenger Services Department (PSD) at Luton Airport.
Thus, passengers were boarded with a seat distribution for a center of gravity (CG) corresponding to the A320. This left the rear of the cabin unoccupied, which neither the cabin crew nor the dispatcher picked up on.
As the aircraft reached takeoff speed, it failed to respond when the co-pilot, who was flying the plane, applied aft side stick in the usual manner. Nor did it rotate when the pilot significantly increased stick deflection. Only when the takeoff/go-around (TOGA) thrust was engaged by the captain, who was monitoring, did the nose of the plane lift.
Load sheet did not match reality
The problem arose because the actual passenger distribution did not match the load sheet distribution. The latter assumed that passengers were seated equally throughout the cabin, whereas there were none towards the rear end. Thankfully, the aircraft had a normal descent, approach, and landing at Prague Airport.
During the flight, the crew analyzed the issue but concluded that an incorrect stabilizer setting had caused the problem. When it was later discovered that there were no passengers seated in the rear of the cabin, the captain completed a new load sheet. The distribution of passengers in the A321 cabin clearly showed that the aircraft CG was outside of what is known as its permitted envelope.
Wizz updated procedures as a result
Following the incident, Wizz reported it would improve the passage of information from its control center. The airline would also include any aircraft type changes at the flight briefing. Furthermore, it would offer additional training for cabin crew on weight and balance distribution, and issue a crew order with enhanced guidance if any suspicion is raised on board.
What is CG?
The center of gravity is the point over which an aircraft would balance. To make sure that a plane is safe to fly, the CG has to fall within limits decided by the aircraft manufacturer. This is the reason why on some smaller airplanes that also carry cargo, the exact weight of passengers may need to be decided for proper distribution.
Just a little over a year ago, German flag-carrier Lufthansa stopped selling the last row of its A320neos, following EASA concerns over the center of gravity limitations.