Investigators found that a series of ‘Miss' identifications caused a ‘serious incident’ at Birmingham Airport last year
Investigators have concluded that a take-off weight error which caused a TUI Airways Boeing 737 to depart Birmingham Airport last year more than one tonne heavier than calculated, was caused by an IT fault which incorrectly attributed a child’s weight to all female passengers using the title ‘Miss’.
The jet, G-TAWG (c/n 37266), was completing a flight between the Midlands gateway and Palma de Mallorca in Spain on July 21 last year when the “serious incident” occurred.
The issue was first identified on July 10, when three adult females were checked in for a flight as children and the reason was discovered to be related to the use of the title ‘Miss’, which the system interpreted as an infant and not an adult. The weight for each person was then recorded as 35kg instead of 69kg.
Whiskey Golf was the first of three flights to depart on the day of the incident at 0500hrs from Birmingham. The flight crew had two documents available to them which were the flight plan showing the route and planning information with predicted take-off weight, and a load sheet providing the actual weight and spread of passengers.
The Air Accidents Investigation Branch (AAIB) says 38 female travellers were misidentified as children which meant the load sheet generated for the flight was more than 1,200kg below the actual aircraft weight.
The flight crew reviewed both the flight plan – which gave an expected take-off weight (TOW) of 64,889kg – and the load sheet which showed a TOW of 64,889kg. According to the report, the pilots noticed the difference of 1,606kg between the two figures and that the number of children shown on the load sheet was higher than expected at 65, compared to the 29 which were listed on the flight plan.
The commander recalled thinking that the number was high but plausible because of the disruption caused by the pandemic.
After a brief discussion, the flight crew decided they were content with the load sheet and following the calculation of take-off data, departed normally and continued to destination without issue.
In its analysis, the AAIB concluded that the misidentification of passengers was caused by a simple flaw in the programming of the IT system which produced the load sheet. This issue stemmed from the software being developed in a country where ‘Miss’ is a child and ‘Ms’ is an adult female.
Whilst an incorrect take-off weight was used for aircraft performance planning, the thrust required for the actual TOW and environmental conditions (88.2% N1) was marginally less than the thrust used for the take-off (88.3% N1). The small difference meant the safe operation of the aircraft was not compromised, according to the AAIB.
When the problem was first identified (July 10), the operator had instigated a safety action plan to prevent incorrect load sheets being produced and used for performance planning.
However, the work correcting the data was handled by teams that were not working over the weekend, and programmers were also still actively working on improvements on July 20, which meant incorrectly assigned passenger weights were not amended.
An upgrade of the system producing load sheets was carried out by the operator to prevent reoccurrence.