Narrative:

There was a 1;500 pound increase when the final weights came in. The first officer entered the revised takeoff gross weight (TOGW) and requested a revised takeoff performance message in ACARS. When the message came the airspeeds were significantly lower than the planned takeoff performance speeds. We were number one for takeoff. I told the crew; 'we need to discuss this;' [so] I stopped the aircraft short of the hold line to prevent blocking the runway and set the brakes. The first officer and relief pilot reviewed the takeoff performance message. They both concurred that the numbers looked accurate. I did not look at the message until later. After a discussion of several minutes we accepted the airspeed changes and took the runway. The first officer made the takeoff. He intentionally delayed rotation a few knots after 'rotate.' the rotation rate was normal; 2 1/2 degrees per second. I was looking at the engine instruments at the time of rotation and did not see the attitude indication on the eadi; but it felt normal and looked normal in my periphery vision out the windshield; not excessively nose high. I noticed a very subtle sensation at liftoff; but not the expected thump or bump. It felt as if the wheels hit a small puddle of water. It was so subtle I would not have mentioned it if the flight attendants had not called a few minutes later to report a scrapping sound on takeoff. We did not get a tail skid EICAS message or any other abnormal messages or physical indications. Acceleration was normal; as was the climb rate.when we got above sterile cockpit level we sent a maintenance message saying we had a possible tail skid strike; based on what the flight attendant had told us. Then we reviewed the takeoff performance messages; both the planned message and the final. I noticed a difference of nearly 100;000 pounds in the assumed TOGW between the two. The first officer had entered 286.5 as the TOGW when he should have entered 386.5.we then checked the QRH for tail strike procedures. The QRH directed that in case of a tail strike we should not pressurize. It made no mention of whether an EICAS message needed to be displayed to trigger the checklist. That prompted me to place a satcom call to dispatch asking for a patch to maintenance to get their input on whether we should depressurize and divert or continue. Duty manager also got in on the discussion. The cabin pressure was holding steady and there were no unusual trim indications or vibrations. Maintenance; duty manager and I all agreed that the best course of action was to continue with the planned flight. A few minutes later duty manager sent an ACARS saying that he had consulted with the training center fleet specialists. They said that absent an EICAS; a pressurization problem or any other abnormal indication; QRH compliance is not required; and they concurred with the decision to continue.after block-in at our destination; a mechanic came up and briefed us on the skid condition; including showing us a photograph. He said the scrape was minor and well within the normal wear limits of the skid. It needed only re-painting. There was no damage to other parts of the aircraft. He said he would follow-up with more inspection but he knew we wanted to know what had happened and thus came up to give us his initial assessment.in summary; the first officer entered a wrong number. It was a simple mistake but it was the digit on the far left and that was the big one. That action produced an ACARS message that the three of us instantly recognized as odd. The flying first officer then asked the non-flying relief pilot to double check the message. The relief pilot looked at the numbers and said they were ok. They both erred. My error was not keeping those brakes set until all doubt was removed. I was the last safety net. The responsibility is mine.a mitigating factor is the performance computer's takeoff performance logic. We have become accustomed to seeing speed bugconfigurations that we have never experienced in the past and I think that was a factor that lured us into the trap. But let it not be interpreted that I make this as an excuse. In summary I think we handled the threat well. We recognized the red flag; we verbalized; coordinated and asked for back-up support from each other. Error repair was our failure.

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Original NASA ASRS Text

Title: A B767 First Officer entered an ACARS revised takeoff weight one hundred thousand pounds too light; so after takeoff the aft flight attendants reported a tail strike. The flight continued to the filed destination where a minor tail strike with no damage was discovered.

Narrative: There was a 1;500 LB increase when the final weights came in. The First Officer entered the revised takeoff gross weight (TOGW) and requested a revised takeoff performance message in ACARS. When the message came the airspeeds were significantly lower than the planned takeoff performance speeds. We were number one for takeoff. I told the crew; 'We need to discuss this;' [so] I stopped the aircraft short of the hold line to prevent blocking the runway and set the brakes. The First Officer and Relief Pilot reviewed the takeoff performance message. They both concurred that the numbers looked accurate. I did not look at the message until later. After a discussion of several minutes we accepted the airspeed changes and took the runway. The First Officer made the takeoff. He intentionally delayed rotation a few knots after 'rotate.' The rotation rate was normal; 2 1/2 degrees per second. I was looking at the engine instruments at the time of rotation and did not see the attitude indication on the EADI; but it felt normal and looked normal in my periphery vision out the windshield; not excessively nose high. I noticed a very subtle sensation at liftoff; but not the expected thump or bump. It felt as if the wheels hit a small puddle of water. It was so subtle I would not have mentioned it if the flight attendants had not called a few minutes later to report a scrapping sound on takeoff. We did not get a TAIL SKID EICAS message or any other abnormal messages or physical indications. Acceleration was normal; as was the climb rate.When we got above sterile cockpit level we sent a maintenance message saying we had a possible tail skid strike; based on what the Flight Attendant had told us. Then we reviewed the takeoff performance messages; both the planned message and the final. I noticed a difference of nearly 100;000 LBS in the assumed TOGW between the two. The First Officer had entered 286.5 as the TOGW when he should have entered 386.5.We then checked the QRH for tail strike procedures. The QRH directed that in case of a tail strike we should not pressurize. It made no mention of whether an EICAS message needed to be displayed to trigger the checklist. That prompted me to place a SATCOM call to Dispatch asking for a patch to Maintenance to get their input on whether we should depressurize and divert or continue. Duty Manager also got in on the discussion. The cabin pressure was holding steady and there were no unusual trim indications or vibrations. Maintenance; Duty Manager and I all agreed that the best course of action was to continue with the planned flight. A few minutes later Duty Manager sent an ACARS saying that he had consulted with the Training Center fleet specialists. They said that absent an EICAS; a pressurization problem or any other abnormal indication; QRH compliance is not required; and they concurred with the decision to continue.After block-in at our destination; a Mechanic came up and briefed us on the skid condition; including showing us a photograph. He said the scrape was minor and well within the normal wear limits of the skid. It needed only re-painting. There was no damage to other parts of the aircraft. He said he would follow-up with more inspection but he knew we wanted to know what had happened and thus came up to give us his initial assessment.In summary; the First Officer entered a wrong number. It was a simple mistake but it was the digit on the far left and that was the big one. That action produced an ACARS message that the three of us instantly recognized as odd. The flying First Officer then asked the non-flying Relief Pilot to double check the message. The Relief Pilot looked at the numbers and said they were OK. They both erred. My error was not keeping those brakes set until all doubt was removed. I was the last safety net. The responsibility is mine.A mitigating factor is the performance computer's takeoff performance logic. We have become accustomed to seeing speed bugconfigurations that we have never experienced in the past and I think that was a factor that lured us into the trap. But let it not be interpreted that I make this as an excuse. In summary I think we handled the threat well. We recognized the red flag; we verbalized; coordinated and asked for back-up support from each other. Error repair was our failure.

Data retrieved from NASA's ASRS site as of July 2013 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.