Date: 201504
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: S
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Human factors: Human-Machine Interface; Communication Breakdown; Workload
Second reporter function: Captain; Pilot Flying
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: We planned on departing 15R and programmed the FMGCs accordingly. We also obtained performance for 15L in case we got switched to that runway for departure. The we later ordered performance for 15L; expecting to receive an updated Zero Fuel Weight (ZFW) and takeoff weight; in case tower launched us from there. Mid taxi we did get switched to 15L and changed runways and entered the flaps and speeds from the performance printout for that runway and intersection; and then we completed the checklists.The takeoff was normal with the nose raised at VR and smoothly transitioned to flight; with a substantial amount of runway remaining. After liftoff I notice V2 had dropped below VLS; lowest selectable speed; and managed speed had moved to the upper end of the speed tape. When leveled off at cruise I took another look at our performance printouts and discovered the last performance numbers we received from Sabre; were for 138.3 and not our final weight of 156.2. Minimum Takeoff Gross Weight (MTOG) for that intersection was 169.7. It appears we took off with V-speed for well below our actual weight; which explains the unusual speed bug behavior. What remains a question is how we ended up with Sabre performance for a weight so far below our actual take-off weight.


Second narrative: During the preflight the First Officer (FO) had pulled up runway data for full length 15R and 15L. Since we were going west on departure we anticipated a 15R full length takeoff. 15L full length was our backup plan and I thought it would be a good idea to get 15L data from intersection wv as a backup to the backup. I requested data from ACARS for runway 15L at [an] intersection using the ACARS runway code. Runway 15R was entered into MCDU with applicable V-speeds; flap setting; and Flex temp. I never looked at the 15LA numbers and did not print them since I thought there was a small chance of using them. I did mention to the FO that those numbers were available on acars.After a delay for bags we departed roughly 30 minutes late. We performed a single engine taxi across the RA bridge to spot 2 near the taxiway. The second engine was started and we were issued a clearance to taxi for takeoff on 15L at [an] intersection. The runway was changed and the ACARS numbers for 15L were entered in the MCDU. On takeoff roll; upon hearing 'rotate'; I executed a nose up; aft stick movement and immediately sensed something wasn't right. The airplane responded sluggishly and I immediately stopped the rotation with main gear wheels still on the runway. I knew we had 12;000 feet of runway and decided to just let the aircraft fly off the runway without increasing AOA.I did notice Vls approach the speed I was flying after rotation and it got to approximately 10-15 knots below actual speed. Once airborne the gear and flaps were retracted and we flew the departure. After level off we looked at the numbers. The numbers had a gross weight of 138.0 and the 15L numbers had a gross weight 156.2. It was then I realized I must've entered the numbers incorrectly; much to my horror.


Synopsis: An A320 crew; relying on incorrect V speeds and weights; rotated and did not take off. The Captain maintained the takeoff attitude and let the aircraft fly itself off the runway. Once established in cruise; the crew compared the performance printouts and discovered the last performance numbers received from Sabre; were for 138.3 and not the final weight of 156.2.