Narrative:

It was the first officer's leg. ATIS reported low ceilings, 3/4 mi visibility, wind 130/17, expect NDB to runway 9, but dlh approach offered radar vectors to ILS runway 27. Checked that the tailwind was within limits and accepted. Shortly before joining final approach course, dlh reported RVR 27 as 2600 touchdown, 6000 rollout. A moment later, they reported the 'sequenced flashers' OTS (this was not noted in our paperwork). Made a quick check of the approach plate and saw that 'ALS' out raised the mins to RVR 4000 or 3/4 mi, but saw no reference to 'sequenced flashers' out. Asked the first officer if he was aware of any restriction, he said no. Continued the approach. Just outside the FAF, dlh reported touchdown RVR 2400, rollout 5000 and cleared us to land. Flew the approach to mins, saw neither runway nor approach lights, and executed a missed approach. Before we could set up another approach the field went well below mins and we proceeded to our alternate. With time to kill before our next flight, I decided to dig through the books to confirm my belief that sequenced flashers were not required for that approach. 2 days later, I am now convinced sequenced flashers were required. What led me to make such a stupid error? A) complacency. I've been a captain for 7 1/2 yrs and routinely review all my manuals, but almost 4 yrs have passed since I last dug deeply into the dry world of operations specifications or detailed descriptions of the various approach light system. As a result, I had forgotten that sequenced flashers are an integral part of the maslr system at dlh and as such are required for approachs to less than RVR 4000. B) assumptions. I assumed that since the operations specifications specifically require sequenced flashers for CAT ii approachs but do not specifically require them for CAT I approachs, they were not required. I also assumed that my first officer would recognize an error should I make one. Both assumptions were in error. C) haste. Pushed by having received the information concerning the inoperative sequenced flashers late in the approach and spurred by the knowledge the WX was deteriorating rapidly, I made only a brief examination of the books and found only what I wanted to find. I should have been more thorough. D) inadequate attention to the information available. Had my release papers noted the inoperative flashers, or had dlh said 'the approach light system is not fully functional', I would have had no trouble avoiding my mistake. Still, I was given more than enough clues to avoid my error had I only been more open to them and less intent on landing ahead of the fob. Call this 'get initis' or tunnel vision. To avoid repeating this blunder, I must study more, listen closely, and think.

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Original NASA ASRS Text

Title: ACR MLG FLEW AN APCH TO DLH IN WX RPTED BELOW REQUIRED MINS.

Narrative: IT WAS THE FO'S LEG. ATIS RPTED LOW CEILINGS, 3/4 MI VISIBILITY, WIND 130/17, EXPECT NDB TO RWY 9, BUT DLH APCH OFFERED RADAR VECTORS TO ILS RWY 27. CHKED THAT THE TAILWIND WAS WITHIN LIMITS AND ACCEPTED. SHORTLY BEFORE JOINING FINAL APCH COURSE, DLH RPTED RVR 27 AS 2600 TOUCHDOWN, 6000 ROLLOUT. A MOMENT LATER, THEY RPTED THE 'SEQUENCED FLASHERS' OTS (THIS WAS NOT NOTED IN OUR PAPERWORK). MADE A QUICK CHK OF THE APCH PLATE AND SAW THAT 'ALS' OUT RAISED THE MINS TO RVR 4000 OR 3/4 MI, BUT SAW NO REF TO 'SEQUENCED FLASHERS' OUT. ASKED THE FO IF HE WAS AWARE OF ANY RESTRICTION, HE SAID NO. CONTINUED THE APCH. JUST OUTSIDE THE FAF, DLH RPTED TOUCHDOWN RVR 2400, ROLLOUT 5000 AND CLRED US TO LAND. FLEW THE APCH TO MINS, SAW NEITHER RWY NOR APCH LIGHTS, AND EXECUTED A MISSED APCH. BEFORE WE COULD SET UP ANOTHER APCH THE FIELD WENT WELL BELOW MINS AND WE PROCEEDED TO OUR ALTERNATE. WITH TIME TO KILL BEFORE OUR NEXT FLT, I DECIDED TO DIG THROUGH THE BOOKS TO CONFIRM MY BELIEF THAT SEQUENCED FLASHERS WERE NOT REQUIRED FOR THAT APCH. 2 DAYS LATER, I AM NOW CONVINCED SEQUENCED FLASHERS WERE REQUIRED. WHAT LED ME TO MAKE SUCH A STUPID ERROR? A) COMPLACENCY. I'VE BEEN A CAPT FOR 7 1/2 YRS AND ROUTINELY REVIEW ALL MY MANUALS, BUT ALMOST 4 YRS HAVE PASSED SINCE I LAST DUG DEEPLY INTO THE DRY WORLD OF OPS SPECS OR DETAILED DESCRIPTIONS OF THE VARIOUS APCH LIGHT SYS. AS A RESULT, I HAD FORGOTTEN THAT SEQUENCED FLASHERS ARE AN INTEGRAL PART OF THE MASLR SYS AT DLH AND AS SUCH ARE REQUIRED FOR APCHS TO LESS THAN RVR 4000. B) ASSUMPTIONS. I ASSUMED THAT SINCE THE OPS SPECS SPECIFICALLY REQUIRE SEQUENCED FLASHERS FOR CAT II APCHS BUT DO NOT SPECIFICALLY REQUIRE THEM FOR CAT I APCHS, THEY WERE NOT REQUIRED. I ALSO ASSUMED THAT MY FO WOULD RECOGNIZE AN ERROR SHOULD I MAKE ONE. BOTH ASSUMPTIONS WERE IN ERROR. C) HASTE. PUSHED BY HAVING RECEIVED THE INFO CONCERNING THE INOP SEQUENCED FLASHERS LATE IN THE APCH AND SPURRED BY THE KNOWLEDGE THE WX WAS DETERIORATING RAPIDLY, I MADE ONLY A BRIEF EXAMINATION OF THE BOOKS AND FOUND ONLY WHAT I WANTED TO FIND. I SHOULD HAVE BEEN MORE THOROUGH. D) INADEQUATE ATTN TO THE INFO AVAILABLE. HAD MY RELEASE PAPERS NOTED THE INOP FLASHERS, OR HAD DLH SAID 'THE APCH LIGHT SYS IS NOT FULLY FUNCTIONAL', I WOULD HAVE HAD NO TROUBLE AVOIDING MY MISTAKE. STILL, I WAS GIVEN MORE THAN ENOUGH CLUES TO AVOID MY ERROR HAD I ONLY BEEN MORE OPEN TO THEM AND LESS INTENT ON LNDG AHEAD OF THE FOB. CALL THIS 'GET INITIS' OR TUNNEL VISION. TO AVOID REPEATING THIS BLUNDER, I MUST STUDY MORE, LISTEN CLOSELY, AND THINK.

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.