A programming error in the software used by UK airline TUI to check-in passengers led to miscalculated flight loads on three flights last July, a potentially serious safety issue.

The error occurred, according to a report released on Thursday by the UK Air Accidents Investigation Branch (AAIB), because the check-in software treated travelers identified as “Miss” in the passenger list as children, and assigned them a weight of 35 kg (~77 lbs) instead of 69 kg (~152 lbs) for an adult.

The AAIB report attributes the error to cultural differences in how the term Miss is understood.

“The system programming was not carried out in the UK, and in the country where it was performed the title Miss was used for a child, and Ms for an adult female, hence the error,” the report says.

— Airline software super-bug: Flight loads miscalculated because women using ‘Miss’ were treated as children