Narrative:

Recently I was involved in a harrowing experience while flying overseas in a B747-400. One of the 'features' of this plane is a fail safe or 'fail operational' design used for flying instrument approachs. Unfortunately, this design crippled the cockpit crew for about 1 min while we worked feverishly to rectify the problem. I was flying a CAT I ILS approach to the active runway. The autoplt was on and the localizer was 'captured.' a rainstorm over the field closed the active runway and the controller issued us clearance to land on a parallel runway. (The rain was heavy, but not red on WX radar.) since we had already captured the localizer to the previous runway, heading select mode was disabled. So in order to comply with the controller's new heading to intercept the new localizer, I had to turn off the autoplt and fly to that heading manually. (Flight directors are also inoperative at this point.) meanwhile, the captain is trying to reselect the new runway so we can pick up the new localizer. The fail operational design would not allow him to select a new runway either on the 'navrad' page or the departure/arrival page. While we 'flailed along' on this miserable approach, I thought of going missed approach, but guess what? I have no way to fly it because the localizer is still tuned to the wrong runway! My map display is no good and all I have is a $150 million J-3 cub with 440 people on board! Finally, we remembered from training that the only way to free up the CDU is by physically turning off both flight directors and the autoplt. Then and only then can you select a new runway. I captured the localizer and was high on the GS, broke out and landed. Please advise boeing that they must add a new selection on the departure/arrival page that allows switching runways without turning off the autoplt and flight directors.

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Original NASA ASRS Text

Title: FO, PF, ON A B747-400 TELLS OF DIFFICULTY IN ACQUIRING THE ILS OF A PARALLEL RWY FOR A 'SIDE-STEP MANEUVER.' PRIMARY RWY HAD JUST BEEN CLOSED BY RAIN SHOWERS AT A FOREIGN ARPT. CTLR ASKED FLT TO MOVE TO THE PARALLEL RWY. THEY COULD NOT GET THE CDU TO ACCEPT THE NEW ILS FREQ FOR APCH UNTIL BOTH THE AUTOPLT AND BOTH FLT DIRECTORS WERE CYCLED OFF AND BACK ON. THIS RESULTED IN A DESTABILIZED APCH WITH A 200 FT CEILING. RPTR CALLS FOR AN ADDITIONAL OPTION ON THE ARR DEP PAGE SO AS TO AVOID THIS 'OFF AND ON' OP. AN ANONYMOUS RPT.

Narrative: RECENTLY I WAS INVOLVED IN A HARROWING EXPERIENCE WHILE FLYING OVERSEAS IN A B747-400. ONE OF THE 'FEATURES' OF THIS PLANE IS A FAIL SAFE OR 'FAIL OPERATIONAL' DESIGN USED FOR FLYING INST APCHS. UNFORTUNATELY, THIS DESIGN CRIPPLED THE COCKPIT CREW FOR ABOUT 1 MIN WHILE WE WORKED FEVERISHLY TO RECTIFY THE PROB. I WAS FLYING A CAT I ILS APCH TO THE ACTIVE RWY. THE AUTOPLT WAS ON AND THE LOC WAS 'CAPTURED.' A RAINSTORM OVER THE FIELD CLOSED THE ACTIVE RWY AND THE CTLR ISSUED US CLRNC TO LAND ON A PARALLEL RWY. (THE RAIN WAS HVY, BUT NOT RED ON WX RADAR.) SINCE WE HAD ALREADY CAPTURED THE LOC TO THE PREVIOUS RWY, HDG SELECT MODE WAS DISABLED. SO IN ORDER TO COMPLY WITH THE CTLR'S NEW HDG TO INTERCEPT THE NEW LOC, I HAD TO TURN OFF THE AUTOPLT AND FLY TO THAT HDG MANUALLY. (FLT DIRECTORS ARE ALSO INOP AT THIS POINT.) MEANWHILE, THE CAPT IS TRYING TO RESELECT THE NEW RWY SO WE CAN PICK UP THE NEW LOC. THE FAIL OPERATIONAL DESIGN WOULD NOT ALLOW HIM TO SELECT A NEW RWY EITHER ON THE 'NAVRAD' PAGE OR THE DEP/ARR PAGE. WHILE WE 'FLAILED ALONG' ON THIS MISERABLE APCH, I THOUGHT OF GOING MISSED APCH, BUT GUESS WHAT? I HAVE NO WAY TO FLY IT BECAUSE THE LOC IS STILL TUNED TO THE WRONG RWY! MY MAP DISPLAY IS NO GOOD AND ALL I HAVE IS A $150 MILLION J-3 CUB WITH 440 PEOPLE ON BOARD! FINALLY, WE REMEMBERED FROM TRAINING THAT THE ONLY WAY TO FREE UP THE CDU IS BY PHYSICALLY TURNING OFF BOTH FLT DIRECTORS AND THE AUTOPLT. THEN AND ONLY THEN CAN YOU SELECT A NEW RWY. I CAPTURED THE LOC AND WAS HIGH ON THE GS, BROKE OUT AND LANDED. PLEASE ADVISE BOEING THAT THEY MUST ADD A NEW SELECTION ON THE DEP/ARR PAGE THAT ALLOWS SWITCHING RWYS WITHOUT TURNING OFF THE AUTOPLT AND FLT DIRECTORS.

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.