Plane reaches height of nearly 15,000 feet and then crew find windows missing. How it happened

A passenger plane departing from London's Stansted Airport had to return back after it had reached an altitude of 14,500 as cabin crew detected missing windows, according to a report from UK Air Accidents Investigation Branch. The Airbus A321 aircraft experienced this issue during a flight last month. The Air Accidents Investigation Branch (AAIB), which is investigating the incident, expressed concerns that this incident could have had more severe consequences.

The aircraft was supposed to go from London Stansted Airport to Orlando International Airport, Florida in the first leg the flight.

"Whereas in this case the damage became apparent at around FL100 or 10,000 feet 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," AAIB said in its report.

According to a report in the Independent, the plane belonged to a a US-based luxury holiday company.

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.

The report stated that 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," the report said.

After plane returned, the crew inspected the aircraft from the outside and saw that two cabin windowpanes were missing and a third was dislodged.

The previous day to the 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, according to the report. These lights were supposed to be deployed at a minimum distance of 10 meters from the subject being illuminated.

The investigation revealed that the windows might 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."

The AAIB determined that the cabin maintained normal pressurization. An examination of the areas around the missing or damaged windows revealed that window retainers were in good condition and correctly installed. The foam ring material on the back of the cabin liners was found to be melted in the areas adjacent to the windows that were damaged or missing.