Passenger traffic dipped by 11.4 per cent last month, while passenger capacity dropped 13.7 per cent.
BA said the walkout affected traffic numbers, which are measured in revenue per passenger kilometre and cost the airline between £40-45m. The strike also affected capacity numbers.
During the work stoppage, the airline flew 79 per cent of its long haul flights and 58 per cent of short haul flights.
Planned winter capacity reductions also accounted for the decline in traffic.
The airline carried 2.2m passengers last month, marking a 14.6 per cent decline on the same period in 2009 when it flew 2.6m passengers.
“Excluding the impact of the cabin crew strikes the underlying traffic volume confirms the trends described previously, with a modest year-on-year improvement in premium traffic and non-premium traffic levels stable,” said the airline’s traffic and capacity report.
Strike talks between BA and the Unite union have yet to restart.