Date: 201907
Local time of day: 0601-1200
Location: ZZZZ.Airport, FO
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Confusion; Situational Awareness
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Weight And Balance; Ground Event / Encounter Ground Strike - Aircraft
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: This was my first trip flying with this Captain. First flight was to ZZZZ in Aircraft X. During my walk-around I took a picture of the tail skid; which had a small amount of green visible on the warning decal. I showed this to the CA (Captain) when I returned to the cockpit for SA (Situational Awareness). All phases of ground ops were normal. Captain was PF (Pilot Flying). We got to know each other more during cruise and found out we lived very close to each other. He thoroughly briefed the planned arrival and landing into ZZZZ. We reviewed all Jepps thoroughly and complied with all checklists. He flew the ILS Runway 07 to a very good landing. We had normal ground ops at ZZZZ. [The next day] when we arrived at the aircraft our FAs (Flight Attendants) from the prior day were on board. During my walk-around I found the tail skid had the same small amount of green visible on the warning decal as the day prior; so I did not take a picture as it was exactly the same as the day prior. I updated the CA with this info when I returned to the cockpit. My preflight ops were normal. I got departure clearance and final weights came in. I rejected the FMC (Flight Management Computer) takeoff data because the GW (Gross Weight) was 160.7 and the TOW (Take-off Weight) was 160.2. I requested ACARS takeoff performance for 160.7. I was expecting to do this because the CA had added on an extra 1000 fuel for weather. During pushback and engine start ACARS alerts were received by both of us and the FMC was updated. I checked the take-off data for correct altitudes. I set flaps 1 and called ground for taxi. During taxi; the before takeoff checklist was accomplished. I was verbalizing ACARS printouts on my yoke and verifying on the FMC pages. I set V2 of 130 in the speed window. I said that was a low V2. I adjusted the trim. We gave way to an aircraft crossing on 'G' as we taxied down 'A' and monitored Tower. When we got to the end of the taxiway; the CA asked if we were all caught up and I said we were. We transferred aircraft control lined up on centerline for Runway X. I held the brakes with my feet. Once cleared; takeoff roll began and I rotated at VR of 124. The aircraft felt light and different during my slow pull back on the yoke; so I slowly pulled a little more. It felt like a long time for the aircraft to lift off. I felt and heard a thump. I saw the taxiway for Runway XX to the right. Once airborne; the gear was retracted; I said that we met 3460 ft; then the CA said to watch my speed. I lowered the nose and the stick shaker activated. I lowered the nose again and we began to accelerate and continued turn and climb for ZZZZZ above 5000 ft in VNAV/LNAV. An FA called and confirmed the tail strike. We cleaned up the aircraft; accomplished the After Takeoff checklist and checked in with Departure. We wanted to get above the MSA (Minimum Sector Altitude) of 12900 ft before accomplishing another checklist. The autopilot was on and the CA started the Tailstrike checklist. We were above 18000 ft when the CA was able to coordinate a descent and fix for a holding pattern to burn fuel. We did not declare an emergency because we were unable return to ZZZZ due to our weight. Once below 10000 ft we manually depressurized the aircraft and entered a holding pattern at ZZZZZ1 at 9000 ft and 230 kts. ATC moved the holding pattern to ZZZZZ2 at 9000. In the holding pattern when the Tailstrike checklist was complete; the CA talked to the FAs; Dispatch and the passengers. The aircraft was stable - we aviated; navigated and communicated; so I started reviewing the ACARS print outs and ACARS messages. I found my error of 106.7 vice the correct weight of 160.7. I found the ACARS take off data warning message of assumed weight 106.7 less than final weight manifest of TOG 160.3. My heart sank! As weather moved in ATC reassigned the holding pattern to ZZZZZ1 at 9000 ft with 10-mile legs. We accomplished the Descent checklist and the CA briefed his approach andlanding for flaps 40 and autobrakes 3; ILS Runway X. ACARS comms were intermittent; so we manually checked landing distance for weight 146.0; applied corrections and verified runway length was greater than 7200 ft needed. The CA flew the ILS Runway X to a very good flaps 40 landing. We had normal ground ops to the gate at ZZZZ. The flight was just over 3 hours. The station wanted to know the CA's plan on what to do with the passengers. They gave the CA a message to call the Chief Pilot. I wanted to do a walk around to see the tail but moved quickly because there were so many people. There was a small amount of red visible on the warning decal on the tail skid. When I returned to the cockpit the Ops General Manager asked the CA to fill out a form and took pictures of our licenses for the [local aviation authority]. Later two [local] officials; who identified themselves as [aviation authority]; wanted information. They did not present any identifications. We asked FA to interpret. After all the passengers deplaned; they needed to move to the aircraft. We coordinated to complete our paperwork in the Operations office. We were delayed exiting Customs because the general declaration from the previous date was not acceptable and required extra coordination. After the CA completed the form for the General Manager; he helped to interpret the additional paperwork for the [local] officials who had followed us to Operations. After coordination with Scheduling we took a taxi to the hotel.




Synopsis: B737 First Officer reported entering an incorrect gross weight into the FMC for obtaining takeoff performance data. Subsequent takeoff resulted in a tail strike.