Date: 201510
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: B737-700
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Human factors: Distraction; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Ground Personnel; Person Flight Crew
When detected: Routine Inspection
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: During the boarding process; we noticed that the boarding had stopped a few times due to some issue with the scanner. Eventually; we had all Passengers onboard and we completed all of the briefings and the Before Start Checklist. I input the numbers from the loading schedule into the performance computer and we then ran the Before Push Checklist. The cockpit area was somewhat dark but I believed to see the numbers on the load sheet that I was expecting. Taxi out was somewhat challenging due to the taxiway layout close to the terminals and I was thinking ahead about our upcoming aircraft swap. After a normal takeoff and climb out; I heard the Company call our flight number asking if we were on frequency. I told the Captain I was leaving COMM 1 temporarily. Replying to Company on COMM 2; Company asked if we were still on the ground at the end of the runway. I stated that we had just taken off and were climbing out; and if there was anything I could help them with. I don't recall exactly what they said; but it didn't seem too important because they essentially said to disregard. Cruise was uneventful. After fully configuring for approach; we noticed that our calculated VRef was below the minimum MASI maneuvering speed and the Captain increased airspeed approximately 10 knots in order to provide a higher margin. A safe and uneventful landing was made. During taxi in; I referenced the loading schedule and noticed that the Passenger count listed was 22; lower than our actual Passenger onboard of 122. It was only then that I realized that our calculated weights were not correct for takeoff and landing due to this discrepancy.  Without question; I need to do a better job of backing up the Captain with verifying the numbers listed on the loading schedule. I lost sight of the 'big picture' when I was inputting the numbers into the performance computer; not making the connection that they were lower than what would be considered 'normal' for our Passenger and fuel load. I am accustomed to the loading schedule always being accurate. I must 'trust but verify' the loading schedule. Obviously; multiple inadvertent human errors occurred in this case and I think it is critical that we have better processes to confirm that all of the information on the loading schedule is correct. I believe that the Dispatcher for each flight should review the final loading schedule as well. Perhaps more intelligent software that can catch potential errors on the loading schedule by cross referencing Passenger counts and fuel loads from other programs would prevent this from happening again. The communication protocol and systems currently in place for notifying the Crew of loading schedule errors after pushback are inadequate. An ACARS function that Ground Ops can use to notify the Crew would be helpful and guarantee that the critical information reaches the cockpit and is clearly understood. Industry best practices need to be researched and implemented so that this never happens again.




Synopsis: B737-700 flight crew discovers during approach that the calculated aircraft weight is dramatically off and adds 10 knots to the approach to compensate. The weight and balance computations were done using a passenger count of 22 instead of the actual count of 122. Ground personnel at the departure airport detected the error and attempted to contact the crew prior to takeoff unsuccessfully. When told that the flight was airborne they elected not to inform the crew of the roughly 18;000 pound discrepancy.