Narrative:

Our ramp weight of 207.1 off the flight plan was entered into the FMS. The flight attendants arrived and the plane was boarded. We received our automated load data sheet and the agent came onboard with the final passenger count and updated weather. When we began the process of inputting the takeoff data into the FMS; we noticed that the zero fuel weight (ZFW) on the load data sheet was significantly lower that what we thought it would be; based on the flight plan that was loaded. We discussed it for a minute or so and verified the fuel load; cargo; and passenger count; and ultimately decided that it was just a lighter airplane. The ZFW of 152.7 was entered into the FMS; giving us a ramp weight of approximately 188.9 and takeoff v-speeds based on this weight or 141/142/143. The takeoff was normal; the enroute portion of the flight was normal; the descent was normal and nothing significant was noted in regards to performance. During the approach phase; we commented on how low the vref speed of 121 KTS was. This had been calculated from the FMS based on our landing weight. While 121 KTS is not an uncommon speed for a light B757; it is uncommon for a full B757 on a 3+ hour flight to be that light. I made a mental note of the slower than usual approach speed and we set our speed bugs to the appropriate airspeeds derived from the FMS. They were 126 (vref+5 KTS)/159/199. The field elevation is about 1;100 ft. The sky was clear with an OAT of almost 40 degrees celsius. We configured slightly earlier than normal and slowed down to allow for a departure off of our landing runway. We then configured to landing flaps 25; with the orange bug set to 126 KTS. I did notice that the auto throttles were holding the erp to about 1.07; which is only slightly higher than normal. I disconnected the autopilot around 1;000 ft; and the auto throttles around 500 ft. I was flying the bottom of the orange speed bug (about 130 KTS) until short final. I set the pitch attitude for a normal flare and brought the thrust levers to idle normally; somewhere between 30-40 ft; and expected a normal touchdown. The actual touchdown was firm; and I flared a bit more in an effort to compensate. We rolled out normally; exited the runway and taxied to the gate. During the deplaning; we heard from flight attendants in the back of the airplane that they heard what sounded like metal scraping during the landing. This obviously caused some concern on my part as well as the captain; so we went out to look at the aft end of the airplane. Upon inspection; the aft water drain mast had scraped the runway upon landing; but it was still intact and affixed to the fuselage. There was no other evidence of damage and no indication of any kind of tail strike. We discussed the fact that due to the firm landing; the compression of the landing gear may have caused the drain mast damage; and we were met by our own maintenance technician. Upon the mechanic's inspection; we asked him how we should write it up in the logbook; and together we decided to enter a write-up of 'firm landing.' the captain then called our dispatcher; told him what happened; and inquired about a load audit due to our lower-than-expected ZFW (and therefore vref numbers); and we left for the hotel. The next morning as we were preparing to deadhead home off the trip; we learned that upon closer review of our load data sheet and a call to the load superintendent; that we had been given paperwork showing 183 passengers (full in a B757) but they were all listed at kid weights. We did not notice this during our review of the load data sheet or the loading of the performance numbers; even though we had commented on the discrepancy between the flight plan and the load data sheet. The airplane ended up being approximately 19;000 pounds heavier than our paperwork showed; and this affected out takeoff and landing numbers. This was verified by our load planning department and an internal email was submitted detailing the fact that the load planning was incorrect. It definitely helps to explain why the airplane reacted the way it did when the thrust levers were brought to idle just before touchdown.

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Original NASA ASRS Text

Title: B757 First Officer reports being dispatched with a full load of passengers but an inaccurate weight and balance sheet; which has listed all passengers at child weights. This is not discovered until after an audit is requested after the drain mast contacts the runway during landing.

Narrative: Our ramp weight of 207.1 off the flight plan was entered into the FMS. The Flight Attendants arrived and the plane was boarded. We received our automated load data sheet and the agent came onboard with the final passenger count and updated weather. When we began the process of inputting the takeoff data into the FMS; we noticed that the zero fuel weight (ZFW) on the load data sheet was significantly lower that what we thought it would be; based on the flight plan that was loaded. We discussed it for a minute or so and verified the fuel load; cargo; and passenger count; and ultimately decided that it was just a lighter airplane. The ZFW of 152.7 was entered into the FMS; giving us a ramp weight of approximately 188.9 and takeoff v-speeds based on this weight or 141/142/143. The takeoff was normal; the enroute portion of the flight was normal; the descent was normal and nothing significant was noted in regards to performance. During the approach phase; we commented on how low the Vref speed of 121 KTS was. This had been calculated from the FMS based on our landing weight. While 121 KTS is not an uncommon speed for a light B757; it is uncommon for a full B757 on a 3+ hour flight to be that light. I made a mental note of the slower than usual approach speed and we set our speed bugs to the appropriate airspeeds derived from the FMS. They were 126 (Vref+5 KTS)/159/199. The field elevation is about 1;100 FT. The sky was clear with an OAT of almost 40 degrees Celsius. We configured slightly earlier than normal and slowed down to allow for a departure off of our landing runway. We then configured to landing flaps 25; with the orange bug set to 126 KTS. I did notice that the auto throttles were holding the ERP to about 1.07; which is only slightly higher than normal. I disconnected the autopilot around 1;000 FT; and the auto throttles around 500 FT. I was flying the bottom of the orange speed bug (about 130 KTS) until short final. I set the pitch attitude for a normal flare and brought the thrust levers to idle normally; somewhere between 30-40 FT; and expected a normal touchdown. The actual touchdown was firm; and I flared a bit more in an effort to compensate. We rolled out normally; exited the runway and taxied to the gate. During the deplaning; we heard from flight attendants in the back of the airplane that they heard what sounded like metal scraping during the landing. This obviously caused some concern on my part as well as the Captain; so we went out to look at the aft end of the airplane. Upon inspection; the aft water drain mast had scraped the runway upon landing; but it was still intact and affixed to the fuselage. There was no other evidence of damage and no indication of any kind of tail strike. We discussed the fact that due to the firm landing; the compression of the landing gear may have caused the drain mast damage; and we were met by our own maintenance technician. Upon the mechanic's inspection; we asked him how we should write it up in the logbook; and together we decided to enter a write-up of 'firm landing.' The Captain then called our Dispatcher; told him what happened; and inquired about a load audit due to our lower-than-expected ZFW (and therefore Vref numbers); and we left for the hotel. The next morning as we were preparing to deadhead home off the trip; we learned that upon closer review of our load data sheet and a call to the Load Superintendent; that we had been given paperwork showing 183 passengers (full in a B757) but they were all listed at KID weights. We did not notice this during our review of the load data sheet or the loading of the performance numbers; even though we had commented on the discrepancy between the flight plan and the load data sheet. The airplane ended up being approximately 19;000 pounds heavier than our paperwork showed; and this affected out takeoff and landing numbers. This was verified by our load planning department and an internal email was submitted detailing the fact that the load planning was incorrect. It definitely helps to explain why the airplane reacted the way it did when the thrust levers were brought to idle just before touchdown.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.