Packs-off T/O
Just a reminder that the Outflow Valve closes during the take-off run, so the cabin does not climb with the aeroplane after take-off. The transition from packs-off to packs-on was always very smooth in my experience. But we only did it when we had a performance shortfall (BA). In fact, if memory serves, our default performance figures were with packs on; so switching them off required a positive increment to Flex Temp or RTOW.