A 100000 pound error in takeoff performance calculations led to early rotation and subsequent tail s...

Attributes
ACN	307484
Time
Date	199506
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lhr
State Reference	FO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : atl
Operator	common carrier : air carrier
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 12000 flight time type : 600
ASRS Report	307484
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : ground less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Due to time compression, I became task rushed and selected a weight and speed card that a previous crew used to land. This weight was approximately 100000 pounds lighter than actual. The 25 number on the card was obscured. References to the weight via checklists were to the CDU not the card. My mistake was the principle cause of the incident. The captain made the takeoff. He realized something was not correct at rotation. He held the aircraft in a 'checked' attitude until there was more airspeed. Regardless, we still barely struck the tail skid (not the tail). Based on normal retraction and eye witness account, with the advise and concurrence of the dispatcher, maintenance and duty manager, the captain elected to continue to sfo. Predicated on previous aircraft incidents etc, I strongly advised the captain to return to lhr. He considered it and due to previously described events, elected to continue and advised me that my input was 'duly noted' and he alone would take responsibility for the decision. I then considered it more responsible to aid the captain as best I could. The captain's flight skills and judgement preempted my error from allowing a severe situation to develop.

Original NASA ASRS Text

Title: A 100000 LB ERROR IN TKOF PERFORMANCE CALCULATIONS LED TO EARLY ROTATION AND SUBSEQUENT TAIL SKID STRIKE ON B767- 300.

Narrative: DUE TO TIME COMPRESSION, I BECAME TASK RUSHED AND SELECTED A WT AND SPD CARD THAT A PREVIOUS CREW USED TO LAND. THIS WT WAS APPROX 100000 LBS LIGHTER THAN ACTUAL. THE 25 NUMBER ON THE CARD WAS OBSCURED. REFS TO THE WT VIA CHKLISTS WERE TO THE CDU NOT THE CARD. MY MISTAKE WAS THE PRINCIPLE CAUSE OF THE INCIDENT. THE CAPT MADE THE TKOF. HE REALIZED SOMETHING WAS NOT CORRECT AT ROTATION. HE HELD THE ACFT IN A 'CHKED' ATTITUDE UNTIL THERE WAS MORE AIRSPD. REGARDLESS, WE STILL BARELY STRUCK THE TAIL SKID (NOT THE TAIL). BASED ON NORMAL RETRACTION AND EYE WITNESS ACCOUNT, WITH THE ADVISE AND CONCURRENCE OF THE DISPATCHER, MAINT AND DUTY MGR, THE CAPT ELECTED TO CONTINUE TO SFO. PREDICATED ON PREVIOUS ACFT INCIDENTS ETC, I STRONGLY ADVISED THE CAPT TO RETURN TO LHR. HE CONSIDERED IT AND DUE TO PREVIOUSLY DESCRIBED EVENTS, ELECTED TO CONTINUE AND ADVISED ME THAT MY INPUT WAS 'DULY NOTED' AND HE ALONE WOULD TAKE RESPONSIBILITY FOR THE DECISION. I THEN CONSIDERED IT MORE RESPONSIBLE TO AID THE CAPT AS BEST I COULD. THE CAPT'S FLT SKILLS AND JUDGEMENT PREEMPTED MY ERROR FROM ALLOWING A SEVERE SIT TO DEVELOP.

Data retrieved from NASA's ASRS site as of July 2007 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.

A 100000 pound error in takeoff performance calculations led to early rotation and subsequent tail skid strike on B767- 300.