Narrative:

Early morning departure from orlando on sep/fri/2005. Power swap from external at 5 to 10 minutes from out time of xa:20 local seemed harder than normal but no indications of problem at that time. On pushback; we get an initialization not complete message. First officer enters gallons boarded. On taxi out after second engine start power swap; we get mcdu scratch pad message 'FMS1/FMS2 gw diff.' first officer checks gw data on FMS2 vs FMS1 and says they match so we continue. My leg to lax and out of 3000 ft AGL I call for managed speed. It doesn't engage and a quick glance at the MCDU1 reveals no calculated data on the ensuing points. MCDU2 does show data. I call for speed 250 and tell the first officer we will deal with the problem above 10000 ft. At 10000 ft; 280 KTS speed is selected and we climb to intermediate leveloff of 16000 ft. I tell the copilot to take the airplane; disengage the autoplt 1; fly for a second and engage autoplt 2; which he does. I then am able to engage managed speed mode. Now airborne; we are unable to reenter the missing fuel weight data into the boxes on the FMS1. There are no other indications of problems with the FMS or related systems and all circuit breakers check good. Approaching descent point on the paradise arrival in lax; we are slowed to 220 KTS for sequencing and then given 250 KTS a short while later for the descent; both of which are set in the selected speed window. During the arrival; I disengage the autoplt 2 and hand fly the airplane. The approach mode is activated and confirmed by the copilot on the FMS2. During the later portions of the arrival; I call for 200 KTS and then 180 KTS to be in a gear down; spoilers; flaps 2 configuration near fuelr intersection. The copilot reads the vapp speed off of the FMS2 and then sets 130 KTS for the final slowdown. We are slightly high still; but coming down nicely to glide path and visual with the runway. Pitch is shallowed; flaps 3 lowered at 175 KTS and flaps full lowered at 167 KTS. I am holding 140 to 145 KTS in the final few hundred ft above capturing glide slope; slightly inside the marker and well above 1000 ft AGL VMC. At this point I am flying pitch for airspeed in idle power. Somewhere around 800 ft; the picture begins to change and over the span of maybe 3 to 5 seconds; the pitch requires a shallowing to avoid increasing speed. Up to this point; my left side mfd and its speed tape indications have all been normal. Now I see a fairly large increasing speed trend arrow at which point my next outside visual crosscheck shows the nose higher than it should be and the aircraft position relative to the runway and desired path going to the high side. Almost immediately; I hear the engines spool up. The throttles are still in automatic mode and power should be at idle but a glance at the EPR gauges shows the power is up now; commensurate with the sound; the power is way up. The copilot hits the perf key on FMS2 to verify the aircraft is in fact in the approach mode. Airspeed is now rapidly increasing; so I raise the nose and catch it at about 180 to 182 KTS. I also disengage the autothrottles with a double click to the red thumb button and I pull both throttle to idle. The power does not come back. Now we are obviously no longer in a position to land the aircraft so I initiate the go around and tell the copilot to tell the tower. I advance both throttles from the idle setting all the way to toga and back two notches to the climb position. This regains control of the automatic throttles in the speed mode at our current speed of 180 KTS. Tower gives us a turn to the left and a climb to 5000 ft. We remain configured at flaps 2 and 180 KTS for the downwind; at which point I again tell the copilot to take the airplane and engage autoplt 2. Perf page on both FMS's now show boxes for entry of the new data for approach. I enter data on the FMS1 and confirm that it transfers to FMS2; which it does. The copilot hand flies the second approach using a selected speed of 130 KTS to uneventful touchdown and rollout. Callback conversation with reporter revealed the following information: reporter stated the big mystery is why mcdu did not indicate a dataloss prior to takeoff. He said the power swap did not feel clean and crisp and was accompanied by a short delay but no abnormal indications at the time. The only indication of a problem was the mcdu message; 'FMS1/FMS2 gw diff.' the first officer was very experienced and reviewed the mcdu's and indicated that the data on all pages was correct. In flight; only the vertical navigation did not function. Reporter believes the lateral navigation was functional. When the crew discovered the missing data; they were unable to enter the data because they were airborne and the airbus mcdu implementation does not allow changing weight data once airborne.

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Original NASA ASRS Text

Title: AN A319 CREW RPTS THE LEFT MCDU LOST DATA DURING GND POWER/SHIP POWER SHIFT; BUT PRESENTED THE CREW WITH NO FAILURE INDICATION.

Narrative: EARLY MORNING DEP FROM ORLANDO ON SEP/FRI/2005. POWER SWAP FROM EXTERNAL AT 5 TO 10 MINUTES FROM OUT TIME OF XA:20 LOCAL SEEMED HARDER THAN NORMAL BUT NO INDICATIONS OF PROB AT THAT TIME. ON PUSHBACK; WE GET AN INITIALIZATION NOT COMPLETE MESSAGE. FO ENTERS GALLONS BOARDED. ON TAXI OUT AFTER SECOND ENG START POWER SWAP; WE GET MCDU SCRATCH PAD MESSAGE 'FMS1/FMS2 GW DIFF.' FO CHECKS GW DATA ON FMS2 VS FMS1 AND SAYS THEY MATCH SO WE CONTINUE. MY LEG TO LAX AND OUT OF 3000 FT AGL I CALL FOR MANAGED SPD. IT DOESN'T ENGAGE AND A QUICK GLANCE AT THE MCDU1 REVEALS NO CALCULATED DATA ON THE ENSUING POINTS. MCDU2 DOES SHOW DATA. I CALL FOR SPD 250 AND TELL THE FO WE WILL DEAL WITH THE PROB ABOVE 10000 FT. AT 10000 FT; 280 KTS SPD IS SELECTED AND WE CLB TO INTERMEDIATE LEVELOFF OF 16000 FT. I TELL THE COPLT TO TAKE THE AIRPLANE; DISENGAGE THE AUTOPLT 1; FLY FOR A SECOND AND ENGAGE AUTOPLT 2; WHICH HE DOES. I THEN AM ABLE TO ENGAGE MANAGED SPD MODE. NOW AIRBORNE; WE ARE UNABLE TO REENTER THE MISSING FUEL WT DATA INTO THE BOXES ON THE FMS1. THERE ARE NO OTHER INDICATIONS OF PROBS WITH THE FMS OR RELATED SYSTEMS AND ALL CIRCUIT BREAKERS CHK GOOD. APCHING DSCNT POINT ON THE PARADISE ARR IN LAX; WE ARE SLOWED TO 220 KTS FOR SEQUENCING AND THEN GIVEN 250 KTS A SHORT WHILE LATER FOR THE DSCNT; BOTH OF WHICH ARE SET IN THE SELECTED SPD WINDOW. DURING THE ARR; I DISENGAGE THE AUTOPLT 2 AND HAND FLY THE AIRPLANE. THE APCH MODE IS ACTIVATED AND CONFIRMED BY THE COPLT ON THE FMS2. DURING THE LATER PORTIONS OF THE ARR; I CALL FOR 200 KTS AND THEN 180 KTS TO BE IN A GEAR DOWN; SPOILERS; FLAPS 2 CONFIGURATION NEAR FUELR INTXN. THE COPLT READS THE VAPP SPD OFF OF THE FMS2 AND THEN SETS 130 KTS FOR THE FINAL SLOWDOWN. WE ARE SLIGHTLY HIGH STILL; BUT COMING DOWN NICELY TO GLIDE PATH AND VISUAL WITH THE RWY. PITCH IS SHALLOWED; FLAPS 3 LOWERED AT 175 KTS AND FLAPS FULL LOWERED AT 167 KTS. I AM HOLDING 140 TO 145 KTS IN THE FINAL FEW HUNDRED FT ABOVE CAPTURING GLIDE SLOPE; SLIGHTLY INSIDE THE MARKER AND WELL ABOVE 1000 FT AGL VMC. AT THIS POINT I AM FLYING PITCH FOR AIRSPD IN IDLE POWER. SOMEWHERE AROUND 800 FT; THE PICTURE BEGINS TO CHANGE AND OVER THE SPAN OF MAYBE 3 TO 5 SECONDS; THE PITCH REQUIRES A SHALLOWING TO AVOID INCREASING SPD. UP TO THIS POINT; MY LEFT SIDE MFD AND ITS SPD TAPE INDICATIONS HAVE ALL BEEN NORMAL. NOW I SEE A FAIRLY LARGE INCREASING SPD TREND ARROW AT WHICH POINT MY NEXT OUTSIDE VISUAL CROSSCHECK SHOWS THE NOSE HIGHER THAN IT SHOULD BE AND THE ACFT POSITION RELATIVE TO THE RWY AND DESIRED PATH GOING TO THE HIGH SIDE. ALMOST IMMEDIATELY; I HEAR THE ENGS SPOOL UP. THE THROTTLES ARE STILL IN AUTO MODE AND POWER SHOULD BE AT IDLE BUT A GLANCE AT THE EPR GAUGES SHOWS THE POWER IS UP NOW; COMMENSURATE WITH THE SOUND; THE POWER IS WAY UP. THE COPLT HITS THE PERF KEY ON FMS2 TO VERIFY THE ACFT IS IN FACT IN THE APCH MODE. AIRSPD IS NOW RAPIDLY INCREASING; SO I RAISE THE NOSE AND CATCH IT AT ABOUT 180 TO 182 KTS. I ALSO DISENGAGE THE AUTOTHROTTLES WITH A DOUBLE CLICK TO THE RED THUMB BUTTON AND I PULL BOTH THROTTLE TO IDLE. THE POWER DOES NOT COME BACK. NOW WE ARE OBVIOUSLY NO LONGER IN A POSITION TO LAND THE ACFT SO I INITIATE THE GO AROUND AND TELL THE COPLT TO TELL THE TWR. I ADVANCE BOTH THROTTLES FROM THE IDLE SETTING ALL THE WAY TO TOGA AND BACK TWO NOTCHES TO THE CLB POSITION. THIS REGAINS CTL OF THE AUTO THROTTLES IN THE SPD MODE AT OUR CURRENT SPD OF 180 KTS. TWR GIVES US A TURN TO THE LEFT AND A CLB TO 5000 FT. WE REMAIN CONFIGURED AT FLAPS 2 AND 180 KTS FOR THE DOWNWIND; AT WHICH POINT I AGAIN TELL THE COPLT TO TAKE THE AIRPLANE AND ENGAGE AUTOPLT 2. PERF PAGE ON BOTH FMS'S NOW SHOW BOXES FOR ENTRY OF THE NEW DATA FOR APCH. I ENTER DATA ON THE FMS1 AND CONFIRM THAT IT TRANSFERS TO FMS2; WHICH IT DOES. THE COPLT HAND FLIES THE SECOND APCH USING A SELECTED SPD OF 130 KTS TO UNEVENTFUL TOUCHDOWN AND ROLLOUT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE BIG MYSTERY IS WHY MCDU DID NOT INDICATE A DATALOSS PRIOR TO TKOF. HE SAID THE POWER SWAP DID NOT FEEL CLEAN AND CRISP AND WAS ACCOMPANIED BY A SHORT DELAY BUT NO ABNORMAL INDICATIONS AT THE TIME. THE ONLY INDICATION OF A PROB WAS THE MCDU MESSAGE; 'FMS1/FMS2 GW DIFF.' THE FO WAS VERY EXPERIENCED AND REVIEWED THE MCDU'S AND INDICATED THAT THE DATA ON ALL PAGES WAS CORRECT. IN FLT; ONLY THE VERT NAV DID NOT FUNCTION. RPTR BELIEVES THE LATERAL NAV WAS FUNCTIONAL. WHEN THE CREW DISCOVERED THE MISSING DATA; THEY WERE UNABLE TO ENTER THE DATA BECAUSE THEY WERE AIRBORNE AND THE AIRBUS MCDU IMPLEMENTATION DOES NOT ALLOW CHANGING WT DATA ONCE AIRBORNE.

Data retrieved from NASA's ASRS site as of January 2009 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.