Date: 201710
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Training / Qualification
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Flight Cancelled / Delayed
Contributing factors: Equipment / Tooling; Human Factors
Primary problem: Human Factors

Narrative: When initially programming the weight and balance and sending off the request; I received an immediate message T/O DATA AVAILABLE; which indicated an error made by me. Verifying everything; I was unable to identify wrong entries so I contacted Dispatch by cellphone. The Dispatcher informed me that the aircraft was 'Locked-out' by Maintenance Control due to unfinished overnight paperwork from last night (the aircraft had come out of Maintenance that morning). At that point it was departure time; and I asked to be connected with Maintenance Control. The gentleman I spoke with was unable to give me an estimate as to when that might be finished; and I relayed that information to the Captain.After an additional 25 or so minutes the Agent entered the cockpit; told us weight and balance performance was down; provided a manual weight and balance schedule and I proceeded to enter the values. According to the form; we had 78 standard passengers and an additional 75(?) nonstandard passengers plus 1;000 pounds cargo. I remember questioning the location of the non-standard passengers but the Agent insisted to enter the value where he indicated; so I did; and the request yielded a reply by the system. I then loaded the FMC and we ran our checklists. The Agent took his manual load sheet and the release and we pushed back about 35 minutes late.I do recall talking about the unusually low takeoff numbers and subsequently about the sluggish performance but with a (thankfully) slow rotation on takeoff nothing really seemed out of the ordinary. At (time) Z we received an ACARS message indicating that our ZFW had been calculated with only 78 Passengers instead of the actual 152. We ran some numbers and estimated to be 12;000 to 15;000 pounds heavier than the load sheet indicated (we had no copy) and I recalculated the landing speeds.At (time) Z Dispatch came back with our revised ZFW of 129;251 and a note that we apparently were 'about 14;000 pounds heavier than the numbers he gave you!' I; again; redid the landing speeds; which had now been within one knot. I can't exactly recall the speeds our wrong ZFW provided; but I think they were over 10 knots slower! A message at (time) Z mentioned that the Dispatcher had filed a report. We landed with no further issues about 20 minutes behind schedule.I believe that more familiarity with manual loading schedules on my part could have prevented this whole scenario. This was only the second time entering values manually and the first time was a ferry with no passengers. I would not have entered the values where the Agent told me to; but could have made a mistake nonetheless. The fact that numbers came back right away lulled me into a false sense of thinking obviously he knew what he was talking about; and the fact that we were late on what the Captain called a high-visibility-charter did not help either. A printed old-style load sheet would also have helped to crosscheck numbers.




Synopsis: B737-800 First Officer reported the automated system was down and the manual weight and balance provided was 14;000 pounds less than the actual weight.