Narrative:

Runway 10L at pdx: WX 1200 scattered, 25000 thin scattered 2 1/2 F, wind 3605, 036/few st 7 heading visibility lwr east. As we called the tower for takeoff clearance, the controller reported visibility 1 1/2, rollout RVR 800, cleared for takeoff. Referring to quick reference, page 4 indicates that for 'standard 3 and 4 engine aircraft,' T/D RVR or 1/2 (tower reported 1 1/2), midfield and rollout rvrs are advisory only. The only remark for that column states: use mid if TDZ inoperative. A more comprehensive study of the page reveals two additional comments at the bottom of the page which state: 'if RVR reports, it controls for specified runways' and 'prevailing visibility reports apply to entire airport.' in this particular situation, the airport was clear with the exception of a fog patch that was blowing across the rollout end of the runway (from the river to the left of the runway). It appears to me that the block on the quick reference chart which states: 'advisory only (if reported)' conflicts with the statement 'if RVR reports, it controls for specified runways.' if this second statement could apply in some situations, then it is my suggestion that a second remark be added to the column: 'standard 3 and 4 engine aircraft' which would reference the, 'if RVR reports...' statement. Supplemental information from acn 171410. As a new second officer, this incident really brought home the need for knowing the book. Although the F/east isn't technically responsible for 'pilot stuff', we could really help in the decision making process in situations like this.

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Original NASA ASRS Text

Title: TKOF BELOW MINIMUMS WHEN REPORTED VISIBILITY MODIFIED BY RVR ROLLOUT GIVEN BY TWR.

Narrative: RWY 10L AT PDX: WX 1200 SCATTERED, 25000 THIN SCATTERED 2 1/2 F, WIND 3605, 036/FEW ST 7 HDG VISIBILITY LWR E. AS WE CALLED THE TWR FOR TKOF CLRNC, THE CTLR RPTED VISIBILITY 1 1/2, ROLLOUT RVR 800, CLRED FOR TKOF. REFERRING TO QUICK REFERENCE, PAGE 4 INDICATES THAT FOR 'STANDARD 3 AND 4 ENG ACFT,' T/D RVR OR 1/2 (TWR RPTED 1 1/2), MIDFIELD AND ROLLOUT RVRS ARE ADVISORY ONLY. THE ONLY REMARK FOR THAT COLUMN STATES: USE MID IF TDZ INOP. A MORE COMPREHENSIVE STUDY OF THE PAGE REVEALS TWO ADDITIONAL COMMENTS AT THE BOTTOM OF THE PAGE WHICH STATE: 'IF RVR RPTS, IT CTLS FOR SPECIFIED RWYS' AND 'PREVAILING VISIBILITY RPTS APPLY TO ENTIRE ARPT.' IN THIS PARTICULAR SITUATION, THE ARPT WAS CLR WITH THE EXCEPTION OF A FOG PATCH THAT WAS BLOWING ACROSS THE ROLLOUT END OF THE RWY (FROM THE RIVER TO THE L OF THE RWY). IT APPEARS TO ME THAT THE BLOCK ON THE QUICK REFERENCE CHART WHICH STATES: 'ADVISORY ONLY (IF RPTED)' CONFLICTS WITH THE STATEMENT 'IF RVR RPTS, IT CTLS FOR SPECIFIED RWYS.' IF THIS SEC STATEMENT COULD APPLY IN SOME SITUATIONS, THEN IT IS MY SUGGESTION THAT A SEC REMARK BE ADDED TO THE COLUMN: 'STANDARD 3 AND 4 ENG ACFT' WHICH WOULD REFERENCE THE, 'IF RVR RPTS...' STATEMENT. SUPPLEMENTAL INFO FROM ACN 171410. AS A NEW S/O, THIS INCIDENT REALLY BROUGHT HOME THE NEED FOR KNOWING THE BOOK. ALTHOUGH THE F/E ISN'T TECHNICALLY RESPONSIBLE FOR 'PLT STUFF', WE COULD REALLY HELP IN THE DECISION MAKING PROCESS IN SITUATIONS LIKE THIS.

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.