Narrative:

Taxiing for takeoff at msp runway 22 at intersection east. Visibility was decreasing and variable from the original ATIS visibility of 2 mi. Following 3 other airline departures, we were cleared into position. Requiring 1/4 mi visibility, we requested the current visibility. We were given 1) ATIS visibility 1/4 mi, then 2) RVR touchdown zone 1000 ft then 3) visibility 1/4 mi. Using the high intensity runway lights as a reference, we estimated approximately 2000 ft visibility as a check to the final 1/4 mi report given. What we were given seemed to be a chronology of visibility choices leading up to the final 1/4 mi report. ATIS reports are not at the moment, RVR reports are continually changing (appropriate at intersection?), then we were given visibility. In variable conditions we need one current, applicable report of the lowest conditions. Supplemental information from acn 405266: we requested visibility from tower as we were cleared onto the runway. Tower gave touchdown zone RVR of 1000 ft and 1/4 mi visibility. Thinking that the RVR may be erroneous, we counted the runway lights to make sure we had 1/4 mi visibility. We estimated visibility to be 2000 ft. We felt that since tower had given us 1/4 mi, and we verified at least that much with the runway lights, we departed.

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Original NASA ASRS Text

Title: B727 CREW TOOK OFF BELOW TKOF MINIMUMS. CAPT USED PREVAILING VISIBILITY RATHER THAN THE CTLING RVR.

Narrative: TAXIING FOR TKOF AT MSP RWY 22 AT INTXN E. VISIBILITY WAS DECREASING AND VARIABLE FROM THE ORIGINAL ATIS VISIBILITY OF 2 MI. FOLLOWING 3 OTHER AIRLINE DEPS, WE WERE CLRED INTO POS. REQUIRING 1/4 MI VISIBILITY, WE REQUESTED THE CURRENT VISIBILITY. WE WERE GIVEN 1) ATIS VISIBILITY 1/4 MI, THEN 2) RVR TOUCHDOWN ZONE 1000 FT THEN 3) VISIBILITY 1/4 MI. USING THE HIGH INTENSITY RWY LIGHTS AS A REF, WE ESTIMATED APPROX 2000 FT VISIBILITY AS A CHK TO THE FINAL 1/4 MI RPT GIVEN. WHAT WE WERE GIVEN SEEMED TO BE A CHRONOLOGY OF VISIBILITY CHOICES LEADING UP TO THE FINAL 1/4 MI RPT. ATIS RPTS ARE NOT AT THE MOMENT, RVR RPTS ARE CONTINUALLY CHANGING (APPROPRIATE AT INTXN?), THEN WE WERE GIVEN VISIBILITY. IN VARIABLE CONDITIONS WE NEED ONE CURRENT, APPLICABLE RPT OF THE LOWEST CONDITIONS. SUPPLEMENTAL INFO FROM ACN 405266: WE REQUESTED VISIBILITY FROM TWR AS WE WERE CLRED ONTO THE RWY. TWR GAVE TOUCHDOWN ZONE RVR OF 1000 FT AND 1/4 MI VISIBILITY. THINKING THAT THE RVR MAY BE ERRONEOUS, WE COUNTED THE RWY LIGHTS TO MAKE SURE WE HAD 1/4 MI VISIBILITY. WE ESTIMATED VISIBILITY TO BE 2000 FT. WE FELT THAT SINCE TWR HAD GIVEN US 1/4 MI, AND WE VERIFIED AT LEAST THAT MUCH WITH THE RWY LIGHTS, WE DEPARTED.

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.