Narrative:

This is a takeoff incident involving a widebody transport at den in very marginal operating conditions. After approximately 1+45 gate hold for reduced operations (1 runway) and de-ice we were cleared to de-ice pad. While on pad, monitored ground who kept a running narrative of varying RVR and runway conditions. Runway 35L requires RVR 1600 due to no rcl. 35R is 600/600/600 as per page 10-9A den. RVR's had been varying from 1000 to 1600 for approximately 45 mins when ground advised they had a break in arrs and would accept departures. We were told there was approximately 1' estimated snow on both runways at that time (PIREP). We watched an medium large transport de-ice and taxi out and awaited his report back thru ground. Report was successful takeoff, could see centerline lights on roll on 35R. With RVR good only on 35R we elected to de-ice, taxi out and evaluate the situation. Post de-ice we were cleared behind either 1 or 2 aircraft and 1 large transport to runway of choice. We did not see the other aircraft but were cleared to taxi via 35L and Z-3 to 35R. During this taxi we heard ground query 2 landing aircraft about visibility and runway conditions. Report was good visibility on approach, runway slick, braking action fair to poor 35R, difficult to estimate depth. Upon reaching 35R, cleared for takeoff with RVR 800/800/?, call on the roll. We completed all checklists rebriefed wing anti-ice on at 800' AGL and got the engines stabilized. Winds were approximately 20-25 KTS generally down the runway possibly left front. At this time I could see several rcls lights and 4 or 5 runway edge lights. Takeoff was initiated after confirming still cleared for takeoff. Tower advised as we rolled that the new RVR was now 700/800/600. Despite the snow on the arrival end of the runway, I could initially see the rcls. As takeoff roll progressed, they became intermittent, and were finally lost in rapidly deteriorating visibility. At about the same time as the lights became intermittent, there appeared to be a wind shift, causing a trend to drift toward the right side of the runway. As I applied rudder to correct for the drift, I was getting a reduction in traction and it ultimately required a very strong rudder input to arrest the right side-drift. Approaching V1, the captain announced, 'I'm losing everything, continue takeoff!' I checked my instruments, including airspeed, then momentarily glanced outside for the runway lights which were still visible. There still appeared to be a slight drift right, so I rechecked my airspeed, and initiated rotation. During the rotation ground roll segment, the aircraft crossed what felt to be either/or tire ruts in the snow or snow ridges associated with less than full width plowing. This caused a pretty bumpy ride for 1-2 seconds and we became airborne. Liftoff and climb out were normal. Post-flight inspection revealed no evidence of runway excursion or abnormal conditions other than a reported broken bottom rotating beacon, to the aircraft. Supplemental information from acn 138750: I think I should have elected to remain in den. While we may have been legal for the takeoff, legal is not always safe.

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Original NASA ASRS Text

Title: ROUGH TKOF DUE TO RWY CONDITION AND CROSSWIND.

Narrative: THIS IS A TKOF INCIDENT INVOLVING A WDB AT DEN IN VERY MARGINAL OPERATING CONDITIONS. AFTER APPROX 1+45 GATE HOLD FOR REDUCED OPERATIONS (1 RWY) AND DE-ICE WE WERE CLRED TO DE-ICE PAD. WHILE ON PAD, MONITORED GND WHO KEPT A RUNNING NARRATIVE OF VARYING RVR AND RWY CONDITIONS. RWY 35L REQUIRES RVR 1600 DUE TO NO RCL. 35R IS 600/600/600 AS PER PAGE 10-9A DEN. RVR'S HAD BEEN VARYING FROM 1000 TO 1600 FOR APPROX 45 MINS WHEN GND ADVISED THEY HAD A BREAK IN ARRS AND WOULD ACCEPT DEPS. WE WERE TOLD THERE WAS APPROX 1' ESTIMATED SNOW ON BOTH RWYS AT THAT TIME (PIREP). WE WATCHED AN MLG DE-ICE AND TAXI OUT AND AWAITED HIS REPORT BACK THRU GND. REPORT WAS SUCCESSFUL TKOF, COULD SEE CENTERLINE LIGHTS ON ROLL ON 35R. WITH RVR GOOD ONLY ON 35R WE ELECTED TO DE-ICE, TAXI OUT AND EVALUATE THE SITUATION. POST DE-ICE WE WERE CLRED BEHIND EITHER 1 OR 2 ACFT AND 1 LGT TO RWY OF CHOICE. WE DID NOT SEE THE OTHER ACFT BUT WERE CLRED TO TAXI VIA 35L AND Z-3 TO 35R. DURING THIS TAXI WE HEARD GND QUERY 2 LNDG ACFT ABOUT VISIBILITY AND RWY CONDITIONS. REPORT WAS GOOD VISIBILITY ON APCH, RWY SLICK, BRAKING ACTION FAIR TO POOR 35R, DIFFICULT TO ESTIMATE DEPTH. UPON REACHING 35R, CLRED FOR TKOF WITH RVR 800/800/?, CALL ON THE ROLL. WE COMPLETED ALL CHECKLISTS REBRIEFED WING ANTI-ICE ON AT 800' AGL AND GOT THE ENGINES STABILIZED. WINDS WERE APPROX 20-25 KTS GENERALLY DOWN THE RWY POSSIBLY LEFT FRONT. AT THIS TIME I COULD SEE SEVERAL RCLS LIGHTS AND 4 OR 5 RWY EDGE LIGHTS. TKOF WAS INITIATED AFTER CONFIRMING STILL CLRED FOR TKOF. TWR ADVISED AS WE ROLLED THAT THE NEW RVR WAS NOW 700/800/600. DESPITE THE SNOW ON THE ARR END OF THE RWY, I COULD INITIALLY SEE THE RCLS. AS TKOF ROLL PROGRESSED, THEY BECAME INTERMITTENT, AND WERE FINALLY LOST IN RAPIDLY DETERIORATING VISIBILITY. AT ABOUT THE SAME TIME AS THE LIGHTS BECAME INTERMITTENT, THERE APPEARED TO BE A WIND SHIFT, CAUSING A TREND TO DRIFT TOWARD THE RIGHT SIDE OF THE RWY. AS I APPLIED RUDDER TO CORRECT FOR THE DRIFT, I WAS GETTING A REDUCTION IN TRACTION AND IT ULTIMATELY REQUIRED A VERY STRONG RUDDER INPUT TO ARREST THE RIGHT SIDE-DRIFT. APCHING V1, THE CAPT ANNOUNCED, 'I'M LOSING EVERYTHING, CONTINUE TKOF!' I CHECKED MY INSTRUMENTS, INCLUDING AIRSPEED, THEN MOMENTARILY GLANCED OUTSIDE FOR THE RWY LIGHTS WHICH WERE STILL VISIBLE. THERE STILL APPEARED TO BE A SLIGHT DRIFT RIGHT, SO I RECHECKED MY AIRSPEED, AND INITIATED ROTATION. DURING THE ROTATION GND ROLL SEGMENT, THE ACFT CROSSED WHAT FELT TO BE EITHER/OR TIRE RUTS IN THE SNOW OR SNOW RIDGES ASSOCIATED WITH LESS THAN FULL WIDTH PLOWING. THIS CAUSED A PRETTY BUMPY RIDE FOR 1-2 SECONDS AND WE BECAME AIRBORNE. LIFTOFF AND CLIMB OUT WERE NORMAL. POST-FLT INSPECTION REVEALED NO EVIDENCE OF RWY EXCURSION OR ABNORMAL CONDITIONS OTHER THAN A REPORTED BROKEN BOTTOM ROTATING BEACON, TO THE ACFT. SUPPLEMENTAL INFORMATION FROM ACN 138750: I THINK I SHOULD HAVE ELECTED TO REMAIN IN DEN. WHILE WE MAY HAVE BEEN LEGAL FOR THE TKOF, LEGAL IS NOT ALWAYS SAFE.

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.