What happened
On 4 October 2023, an Airbus A321-253NX, registration G-OATW, was operating a positioning flight from London Stansted Airport to Orlando, Florida. The aircraft was carrying 11 crew members and 9 passengers. During the climb through 10,000 feet, the cabin became noticeably noisier and colder. A crew member noticed that a window seal on the left side of the aircraft was flapping in the airflow and the windowpane appeared to have shifted downward.
Upon inspection by the flight crew, it was determined that the aircraft should return to Stansted. The flight crew initiated a descent and landed the aircraft safely at 1151 hrs. Following the flight, a ground inspection revealed that two cabin window assemblies were entirely missing and a third was dislodged. Additionally, fragments of acrylic were found inside the left horizontal stabiliser, which had sustained impact damage.
The investigation
The AAIB investigation focused on the aircraft's activities the previous day, during which it had been used for a filming event on the ground. To simulate a sunrise, high-power floodlights were directed through the cabin windows. These lights were positioned on the right side of the aircraft for approximately five and a half hours and on the left side for roughly four hours.
Examination of the aircraft revealed that the windowpanes had undergone thermal deformation and shrinkage. Specifically, the foam ring material on the interior cabin liners was found to be melted near the affected windows. The investigation also identified that the floodlights used, identified as Maxibrute 12, have a specified minimum distance of 10 metres from the object being illuminated, though evidence suggests they were positioned closer to the fuselage during the filming.
Findings
- The cabin windows sustained thermal damage and distortion due to elevated temperatures caused by the filming lights.
- The windowpanely were deformed and shrunk, preventing them from maintaining an effective seal with the rubber gaskets.
- The floodlights were likely positioned within 10 metres of the aircraft, violating the manufacturer's recommended minimum distance.
- The damage to the left horizontal stabiliser was caused by impact from pieces of the window assembly.