A Special Bulletin is published to raise awareness of a recent occurrence in which several cabin windows on an Airbus A321 were damaged by high power lights used during a filming event.
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The damage was discovered after takeoff on the aircraft’s next flight.
Work is ongoing with the aircraft manufacturer and operator to fully understand the properties of the lights used and how this risk can be managed in future.
Aircraft owners and operators should consider the hazard posed by such activities to minimise the risk of aircraft damage.
The aircraft was scheduled to embark on October 4, 2023, on a multi-day charter away from base with a flight crew consisting of three pilots, an engineer, a load master and six cabin crew.
The first sector was a positioning flight from London Stansted Airport to Orlando International Airport, Florida.
In addition to the 11 crew there were nine passengers on board who were all employees of the tour operator or aircraft operating company.
The passengers sat together in the middle of the aircraft just ahead of the overwing exits.
The aircraft departed a few minutes ahead of schedule and took off from Runway 22.
Several passengers recalled that after takeoff the aircraft cabin seemed noisier and colder than they were used to.
As the aircraft climbed through FL100 and the seatbelt signs were switched off, the loadmaster, who had been seated just in front of the other passengers, walked towards the back of the aircraft.
He noticed the increased cabin noise as he approached the overwing exits and his attention was drawn to a cabin window on the left side of the aircraft.
He observed that the window seal was flapping in the airflow and the windowpane appeared to have slipped down.
He described the cabin noise as ‘loud enough to damage your hearing’.
The loadmaster told the cabin crew and then went to the flight deck to inform the commander.
At this stage the aircraft was climbing past FL130, there were no abnormal indications on the flight deck and the aircraft pressurisation system was operating normally.
The flight crew stopped the climb at FL140 and reduced airspeed whilst the engineer and then the third pilot went to look at the window.
Having inspected the window, it was agreed the aircraft should return to Stansted.
The cabin crew told the passengers to remain seated and keep their seatbelts fastened, and reminded them about the use of oxygen masks if that became necessary.
The cabin was quickly secured and the flight crew initiated a descent, first to FL100 and then to FL90.
They established the aircraft in a hold whilst they completed the overweight landing checklist, confirmed landing performance and briefed for the return to Stansted.
The approach and landing on Runway 22 were uneventful.
Landing at 1151 hrs, the total flight time was 36 minutes.
With the airport RFFS in attendance the aircraft taxied to the apron, where the passengers disembarked normally.
Having parked and shut down, the crew inspected the aircraft from the outside and saw that two cabin windowpanes were missing and a third was dislodged.
During the flight the crew had only been aware of an issue with a single windowpane.
The cabin had remained pressurised normally throughout the flight.
The day before the occurrence flight the aircraft had been used for filming on the ground, during which external lights had been shone through the cabin windows to give the illusion of a sunrise.
The lights were first shone on the right side of the aircraft for approximately five and a half hours, with the light focused on the cabin windows just aft of the overwing exits.
The lights were then moved to the left side of the aircraft where they illuminated a similar area on the left side for approximately four hours.
Photographs taken during filming showed six sets of flood lights on both sides of the aircraft.
The aircraft was fitted with an FDR and CVR which were removed and successfully downloaded at the AAIB.
The flight was captured on both recorders and the CVR confirmed reports from the flight crew interviews.
Two window assemblies were missing, and the inner pane and seal from a third window were displaced but partially retained in the airframe.
A shattered outer pane was recovered from the entrance to a rapid-exit taxiway during a routine runway inspection after the aircraft landed.
A fourth window protruded from the left side of the fuselage.
The four affected windows were adjacent to each other, just aft of the left overwing exit.
The windows appear to have sustained thermal damage and distortion because of elevated temperatures while illuminated for approximately four to five and a half hours during filming activity the day before the flight.
It is likely that the flood lights were positioned closer than 10 m.
Whereas in this case the damage became apparent at around FL100 and the flight was concluded uneventfully, a different level of damage by the same means might have resulted in more serious consequences, especially if window integrity was lost at higher differential pressure. ■