|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1801 To 2400|
|Locale Reference||navaid : ang.vor|
|Altitude||msl single value : 30000|
|Controlling Facilities||artcc : lfff.artcc|
tower : zzz.tower
|Operator||common carrier : air carrier|
|Make Model Name||B767-300 and 300 ER|
|Operating Under FAR Part||Part 121|
|Navigation In Use||other|
|Flight Phase||descent : vacating altitude|
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Experience||flight time last 90 days : 140|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Anomaly||aircraft equipment problem : less severe|
altitude deviation : crossing restriction not met
non adherence : clearance
|Independent Detector||other flight crewa|
|Resolutory Action||flight crew : overcame equipment problem|
flight crew : returned to original clearance
|Problem Areas||Flight Crew Human Performance|
While descending from FL390 to cross ANG VOR at FL280; the center autoplt went into degraded mode. This occurred just as the international relief officer and the captain were preparing to switch after the captain's rest period. I had just copied the ATIS and was getting out the plates for lfpg. The international relief officer was selecting the approach in the FMC. The vertical speed window opened to 1400 FPM. No VNAV or LNAV and we were in heading hold. At the same time the FMC dumped our route showing only lfpg as our active waypoint. The international relief officer was in the left seat; I was in the right seat; and the captain was directing from a standing position between the two of us. We put ANG back in and it became the active waypoint but by this time we were coming close to the VOR. Then the captain directed the international relief officer to reselect the arrival. This being done there was still a gap between the active waypoint and the first point on the arrival. The international relief officer was now flying the airplane to keep us close to our course while I reloaded the airway to connect the active waypoint and the first fix on the arrival. This got our route back but by this time we were right on top of or a little past the active waypoint of ANG. LNAV reengaged so the airplane; of course; wanted a right turn back to the fix when we need a left turn to intercept. The international relief officer did a good job keeping the airplane headed in the correct direction. I then selected intercept legs to our next fix; the first fix on the arrival. The international relief officer set about a 15 degree intercept for the fix and now LNAV had a good route in the box and soon captured the course. We reestablished ourselves on the airway and were on altitude. However; by this time we had missed our crossing altitude and missed our turn. I am not exactly sure by how many feet; but I would guess about 2000-2500 ft over the VOR. As for the turn it did not appear we had gone too far astray by the time we turned towards the airway and reestablished ourselves. We quickly got things sorted out; reconfirmed the altitude with ATC and were back on the correct path and altitude. The whole thing probably took between 1-2 mins. ATC made no comment one way or the other and there were no other aircraft observed on the ads-B. When we arrived at lfpg; the captain wrote up the event and maintenance deferred the center autoplt. The mechanic said he thought we had lost an FCC because it was not receiving good updates. I really am not sure of his diagnosis because of the language barrier during his talk with the captain. We flew the next leg with the center autoplt deferred and things went as normal. I am really not sure why the FMC would have dumped our route and the center autoplt quit. The timing of the event could not have been more inopportune. It seemed like something from a very busy aqp simulation period. The combination of having the crew in transition; descending; setting up for the arrival/approach; losing the autoplt and the route all in one shot made it a challenge. I do think we were able to work well as a crew and get the airplane safely back on course and altitude while reestablishing our data in the FMC. Bottom line; however; is we did indeed miss an altitude and a turn.
Original NASA ASRS Text
Title: B767 FLT CREW REPORTS MISSING CROSSING RESTRICTION DUE TO FMC DROPPING ROUTE DURING DESCENT AND CREW CHANGE IN LFFF AIRSPACE.
Narrative: WHILE DSNDING FROM FL390 TO CROSS ANG VOR AT FL280; THE CTR AUTOPLT WENT INTO DEGRADED MODE. THIS OCCURRED JUST AS THE IRO AND THE CAPT WERE PREPARING TO SWITCH AFTER THE CAPT'S REST PERIOD. I HAD JUST COPIED THE ATIS AND WAS GETTING OUT THE PLATES FOR LFPG. THE IRO WAS SELECTING THE APCH IN THE FMC. THE VERT SPD WINDOW OPENED TO 1400 FPM. NO VNAV OR LNAV AND WE WERE IN HDG HOLD. AT THE SAME TIME THE FMC DUMPED OUR RTE SHOWING ONLY LFPG AS OUR ACTIVE WAYPOINT. THE IRO WAS IN THE L SEAT; I WAS IN THE R SEAT; AND THE CAPT WAS DIRECTING FROM A STANDING POS BTWN THE TWO OF US. WE PUT ANG BACK IN AND IT BECAME THE ACTIVE WAYPOINT BUT BY THIS TIME WE WERE COMING CLOSE TO THE VOR. THEN THE CAPT DIRECTED THE IRO TO RESELECT THE ARR. THIS BEING DONE THERE WAS STILL A GAP BTWN THE ACTIVE WAYPOINT AND THE FIRST POINT ON THE ARR. THE IRO WAS NOW FLYING THE AIRPLANE TO KEEP US CLOSE TO OUR COURSE WHILE I RELOADED THE AIRWAY TO CONNECT THE ACTIVE WAYPOINT AND THE FIRST FIX ON THE ARR. THIS GOT OUR RTE BACK BUT BY THIS TIME WE WERE RIGHT ON TOP OF OR A LITTLE PAST THE ACTIVE WAYPOINT OF ANG. LNAV REENGAGED SO THE AIRPLANE; OF COURSE; WANTED A R TURN BACK TO THE FIX WHEN WE NEED A L TURN TO INTERCEPT. THE IRO DID A GOOD JOB KEEPING THE AIRPLANE HEADED IN THE CORRECT DIRECTION. I THEN SELECTED INTERCEPT LEGS TO OUR NEXT FIX; THE FIRST FIX ON THE ARR. THE IRO SET ABOUT A 15 DEG INTERCEPT FOR THE FIX AND NOW LNAV HAD A GOOD RTE IN THE BOX AND SOON CAPTURED THE COURSE. WE REESTABLISHED OURSELVES ON THE AIRWAY AND WERE ON ALT. HOWEVER; BY THIS TIME WE HAD MISSED OUR XING ALT AND MISSED OUR TURN. I AM NOT EXACTLY SURE BY HOW MANY FEET; BUT I WOULD GUESS ABOUT 2000-2500 FT OVER THE VOR. AS FOR THE TURN IT DID NOT APPEAR WE HAD GONE TOO FAR ASTRAY BY THE TIME WE TURNED TOWARDS THE AIRWAY AND REESTABLISHED OURSELVES. WE QUICKLY GOT THINGS SORTED OUT; RECONFIRMED THE ALT WITH ATC AND WERE BACK ON THE CORRECT PATH AND ALT. THE WHOLE THING PROBABLY TOOK BTWN 1-2 MINS. ATC MADE NO COMMENT ONE WAY OR THE OTHER AND THERE WERE NO OTHER ACFT OBSERVED ON THE ADS-B. WHEN WE ARRIVED AT LFPG; THE CAPT WROTE UP THE EVENT AND MAINT DEFERRED THE CTR AUTOPLT. THE MECH SAID HE THOUGHT WE HAD LOST AN FCC BECAUSE IT WAS NOT RECEIVING GOOD UPDATES. I REALLY AM NOT SURE OF HIS DIAGNOSIS BECAUSE OF THE LANGUAGE BARRIER DURING HIS TALK WITH THE CAPT. WE FLEW THE NEXT LEG WITH THE CTR AUTOPLT DEFERRED AND THINGS WENT AS NORMAL. I AM REALLY NOT SURE WHY THE FMC WOULD HAVE DUMPED OUR RTE AND THE CTR AUTOPLT QUIT. THE TIMING OF THE EVENT COULD NOT HAVE BEEN MORE INOPPORTUNE. IT SEEMED LIKE SOMETHING FROM A VERY BUSY AQP SIMULATION PERIOD. THE COMBINATION OF HAVING THE CREW IN TRANSITION; DSNDING; SETTING UP FOR THE ARR/APCH; LOSING THE AUTOPLT AND THE RTE ALL IN ONE SHOT MADE IT A CHALLENGE. I DO THINK WE WERE ABLE TO WORK WELL AS A CREW AND GET THE AIRPLANE SAFELY BACK ON COURSE AND ALT WHILE REESTABLISHING OUR DATA IN THE FMC. BOTTOM LINE; HOWEVER; IS WE DID INDEED MISS AN ALT AND A TURN.
Data retrieved from NASA's ASRS site as of May 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.