Narrative:

The captain on pretkof brief, indicated he would be delaying rotation to V2 instead of vr due to the x-wind and we would be using maximum thrust, although we were legal for reduced, due to the potential for gusty winds. The tower cleared us for takeoff and gave a steady wind of 220 degree/23 KTS. Takeoff roll was normal except the captain mentioned he was getting a significant burble from the wind coming through the buildings along the south side of the runway. At V1 minus 5K (our V1 call) we got a positive gust of 6K. I call V1 at the appropriate time; immediately called vr and at V2 the captain initiated rotation. The initial rotation rate was faster than normal, but the captain checked it around 11 degree nose up and then continued normal rotation rate from then on. Neither the captain nor I perceived anything abnormal, except the initial rapid rotation rate, which he checked. We were advised by aft F/a that she heard an unusual sound on takeoff. On post-flight, we had scraped the aft lav drain mast very slightly. It was still attached and intact. We both felt the gust, x-wind and down-slope of runway 26L at denver contributed to this incident. I believe we encountered the 'backside' of the gust we received V1 and that caused the initial rapid rotation rate. On a downhill runway the significance of that increases because we lose our buffer margins for tail clearance. We were fortunate. Had the captain not checked the rotation when he did, things might have had a different ending. Supplemental information from acn 163598. Runway 26L at denver has a down-slope on the runway at the point where we takeoff. The runway threshold is 5333' and drops to about 5292' and then rises to 5321' at the far end. This means that somewhere along the runway there is a 41' drop. The drop is more than 1200' from the threshold and I figure the low spot to be about 6800' from the threshold which means that there is a possible slope on the runway of between .8 degrees and 2 degrees. The tail will contact the runway under level conditions with the struts compressed on the medium large transport at 10.8 degrees. This means that under the above circumstances the tail would strike the ground at between 8.8 and 10 degrees.

Google
 

Original NASA ASRS Text

Title: MLG DRAGS TAIL ON RWY CDURING TKOF.

Narrative: THE CAPT ON PRETKOF BRIEF, INDICATED HE WOULD BE DELAYING ROTATION TO V2 INSTEAD OF VR DUE TO THE X-WIND AND WE WOULD BE USING MAX THRUST, ALTHOUGH WE WERE LEGAL FOR REDUCED, DUE TO THE POTENTIAL FOR GUSTY WINDS. THE TWR CLRED US FOR TKOF AND GAVE A STEADY WIND OF 220 DEG/23 KTS. TKOF ROLL WAS NORMAL EXCEPT THE CAPT MENTIONED HE WAS GETTING A SIGNIFICANT BURBLE FROM THE WIND COMING THROUGH THE BUILDINGS ALONG THE S SIDE OF THE RWY. AT V1 MINUS 5K (OUR V1 CALL) WE GOT A POSITIVE GUST OF 6K. I CALL V1 AT THE APPROPRIATE TIME; IMMEDIATELY CALLED VR AND AT V2 THE CAPT INITIATED ROTATION. THE INITIAL ROTATION RATE WAS FASTER THAN NORMAL, BUT THE CAPT CHKED IT AROUND 11 DEG NOSE UP AND THEN CONTINUED NORMAL ROTATION RATE FROM THEN ON. NEITHER THE CAPT NOR I PERCEIVED ANYTHING ABNORMAL, EXCEPT THE INITIAL RAPID ROTATION RATE, WHICH HE CHKED. WE WERE ADVISED BY AFT F/A THAT SHE HEARD AN UNUSUAL SOUND ON TKOF. ON POST-FLT, WE HAD SCRAPED THE AFT LAV DRAIN MAST VERY SLIGHTLY. IT WAS STILL ATTACHED AND INTACT. WE BOTH FELT THE GUST, X-WIND AND DOWN-SLOPE OF RWY 26L AT DENVER CONTRIBUTED TO THIS INCIDENT. I BELIEVE WE ENCOUNTERED THE 'BACKSIDE' OF THE GUST WE RECEIVED V1 AND THAT CAUSED THE INITIAL RAPID ROTATION RATE. ON A DOWNHILL RWY THE SIGNIFICANCE OF THAT INCREASES BECAUSE WE LOSE OUR BUFFER MARGINS FOR TAIL CLRNC. WE WERE FORTUNATE. HAD THE CAPT NOT CHKED THE ROTATION WHEN HE DID, THINGS MIGHT HAVE HAD A DIFFERENT ENDING. SUPPLEMENTAL INFO FROM ACN 163598. RWY 26L AT DENVER HAS A DOWN-SLOPE ON THE RWY AT THE POINT WHERE WE TKOF. THE RWY THRESHOLD IS 5333' AND DROPS TO ABOUT 5292' AND THEN RISES TO 5321' AT THE FAR END. THIS MEANS THAT SOMEWHERE ALONG THE RWY THERE IS A 41' DROP. THE DROP IS MORE THAN 1200' FROM THE THRESHOLD AND I FIGURE THE LOW SPOT TO BE ABOUT 6800' FROM THE THRESHOLD WHICH MEANS THAT THERE IS A POSSIBLE SLOPE ON THE RWY OF BTWN .8 DEGS AND 2 DEGS. THE TAIL WILL CONTACT THE RWY UNDER LEVEL CONDITIONS WITH THE STRUTS COMPRESSED ON THE MLG AT 10.8 DEGS. THIS MEANS THAT UNDER THE ABOVE CIRCUMSTANCES THE TAIL WOULD STRIKE THE GND AT BTWN 8.8 AND 10 DEGS.

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.