B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 188
Human-Machine Interface; Distraction; Communication Breakdown; Training / Qualification
Aircraft Equipment Problem Critical; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Aircraft; Human Factors
Arrived early at airport to find jet was arriving late and had a MEL for the EFB rendering the EFB inoperative for the flights.  We talked with the incoming flight crew about the use of the ACARS PERF function since this was the first time either the First Officer or I have used the ACARS since seeing the bulletin issued earlier this year.  The Agent started to load the aircraft while we performed our preflight flows.  The aircraft was filled with 143 Passengers and we were waiting on the bags to be loaded when the Agent brought down the load sheet.  It had 142 Passengers listed and we requested a new one with the correct amount of Passengers (143) to make sure we had the correct weights.  We ran the Before Start/Originating Checklist and performed all required briefings; discussed the fact that the runway was not wet as originally planned; the takeoff weight was several thousands pounds less than planned; and the temperature was less than planned. Once the second load sheet arrived (bags still being loaded); the ATIS and load sheet data were entered into the ACARS PERF Takeoff page.  The Zero Fuel Weight (ZFW) was entered where the Takeoff Weight (TOW) should have been input.  The information came back with a reduction for the N1s; V Speeds and a normal stopping margin.  We accomplished the Before Push Checklist referencing the ACARS PERF data.  We had trouble with the normal responses to the checklist since there was no EFB being used.  The ZFW was entered correctly on the CDU and when it came to the takeoff weight; I performed my normal flow crosscheck of looking at the Release to compare to the CDU and then comparing it to the EFB and load sheet.  Since the EFB was inop; I did not see that the ZFW was entered in as the TOW on the ACARS Takeoff Data output page.  The forward entry door was closed and the jetway was pulled back.  The bags were loaded and communication was established with the Ground Crew.  Just as we were about to push; the jetway came back to the aircraft and the Agent had another load sheet for us.  Doors were disarmed and the load sheet was retrieved.  The new numbers were loaded and the takeoff data was checked.  Pushback and engine start were normal.  Upon taxi clearance; we were given a runway change to 31.  Taxi speed was slow due to the First Officer being heads down (VFR) retrieving ATIS and reprogramming the ACARS PERF numbers and the Takeoff pages.  Once clearing 31R on the taxi out; the numbers were reviewed again.  The stab trim changed by 0.1 unit and the takeoff was reviewed.  Takeoff clearance was received; power was set (lower than required N1 due to takeoff data weight entry error); but takeoff acceleration and distance seemed normal.  V1 and rotate were called.  Rotation was normal but once airborne the elevator controls seemed sluggish.  That is when we both noticed something was not right and I called for maximum takeoff thrust.  The stall indication on the ADI showed approximately three to four degrees above the pitch command bars.  Once maximum takeoff thrust was applied; the rest of the climbout and flight were uneventful.  We should have referenced the FOM not just previous Crew Member's advice on how to use the ACARS PERF function or relying on our review of the bulletin issued several months before; when performing a new procedure with the automation.   We did not feel rushed throughout the process but were interrupted multiple times during the flows and checklists disrupting our normal flows and thinking patterns while preparing for takeoff.  The format for the ACARS PERF takeoff data page was difficult to read and find where information was located.  We had to toggle back and forth between pages to complete the checklist.   Spelling out TAKEOFF WEIGHT instead of TOW could have prevented us from entering in the ZFW since that is the first item we always enter into the CDU when the EFB is used.  We never enter in the TOW and I think this change of procedure contributed to our improper entry of data causing erroneous takeoff data to be used.
We should have reviewed the alternate ACARS performance computation method in the FOM prior to attempting to use this tool for the first time. The ACARS Takeoff Performance layout could be clearer in fully spelling out Takeoff Weight; instead of the TOW abbreviation; which I believe is different from the EFB. In addition; entering the information in a manner similar to the EFB (i.e.; ZFW and TOW) would be more consistent with how we input these figures across different platforms. Also; we had to toggle back and forth on the output of the ACARS page to complete the Before Push Checklist. This is also inconsistent with the EFB output page and makes for a more difficult crosscheck. Bottom line; we should have been more vigilant in cross checking the data.
A B737-700 First Officer entered the Zero Fuel Weight (ZFW) in the FMC instead of the Takeoff Weight (TOW). After rotation the Captain added full power due to a sluggish aircraft feel and an ADI Stall indication. An inoperative EFB requiring a paper weight and balance contributed to the error.