There was a story in the press this week about a software bug which caused several flights last summer to take off heavier than expected. The source of the problem was that all passengers checking in as ‘Miss’ were assigned a child’s standard weight, even though many were actually adult women.
The AAIB report provides more details on one of the affected flights, from Birmingham to Palma de Mallorca. There were 182 passengers on board and from the load sheet we see that the trip fuel was estimated to be 5,400 kg. This is interesting from a CO2 emissions perspective, because accurately estimating this number is half of the battle for emissions calculators. Here we have the airline’s estimate of the fuel required for this flight. Since they know all the conditions (plane type, weather, route, passengers, cargo) and have a lot of operational data, their estimate is going to be pretty accurate. Every kilogram of jet fuel produces 3.16 kilograms of CO2. Using the trip fuel estimate of 5,400 kg, these 182 passengers were responsible for 17 tonnes of CO2, on average 94 kg each.
Two closing remarks: Firstly, we know that this estimate isn’t completely accurate, since the whole reason behind the incident report is the fact that the plane was 1,244 kg heavier than expected. So the estimated trip fuel will be on the low side. Secondly, as we see here that passenger weight really does have an impact on flight planning, is it fair to assign equal emissions to children and adults? What about passengers who travel with only carry-on baggage? The post-flight carbon offset, using each passenger’s total check in weight and the measured trip fuel, would remove these variations and uncertainties.
AAIB report accessed 2021-04.