It claimed the changes – including freezing pay and cutting crew on long-haul flights – were introduced without consultation.
The union had been set to strike over the issues over Christmas, but a separate High Court action stopped it.
A fresh strike ballot will close on 22 February.
British Airways made a pre-tax loss of £50m in the three months to December 2009.
This was down from the £122m it lost in the same period in 2008.
But the carrier’s pre-tax loss in the nine months to December from £70m to £342m in the same period in 2008.