A319
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Type 1458
Workload; Distraction
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Human Factors; MEL
The airplane had two MELs that needed to be dealt with during taxi out. One for a manual engine start of the number 1 engine; and the other for the Captain's rudder disconnect button being inop for the rudder check. We had XXR loaded into the primary flight plan; with XXL ready to go in the secondary. Because of the potential quick taxi to XXR we had elected to have that in the primary. Received pushback clearance and were told to expect XXL. I chose to keep XXR in the primary; until ATC had given it to us officially. With the procedural demand of the manual engine start; my focus was quickly redirected to managing that. Start was normal and we proceeded to taxi away from the gate area on one engine. Ran the before takeoff checklist to the line in the gate area; prior to contacting ground; and then subsequently started the second engine. Contacted ground and was told to taxi to XXL via X; Y. Once the taxi clearance was received our attention turned to the second MEL and coordinating the rudder check for the final items. Ran the final items portion of the checklist before turning onto Y. With two engines running and a downhill taxi towards XXL on Y our attention now was focused on brake temps. We were cleared to 'line up and wait on XXL;' verified XXL; both of us forgetting that we had never swapped to the secondary flight plan. Cleared for takeoff; and noticed the wrong runway selected during 100 knot callout. We had pulled numbers for both XXL and XXR; and they were the same flap setting; almost identical speeds; same departure procedure; and same T procedure. This was fortunate; as I don't think safety was ever jeopardized; but I fully acknowledge that the results could've been different.
A319 First Officer reported failing to update FMC for a runway change.