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Incidents related to Issue 35 incidents related to this issue.

Issue: mode transitions may be uncommanded (Issue #44)
Description: Automation may change modes without pilot commands to do so, possibly producing surprising behavior.

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  2. Accession Number: 51097
    Synopsis:
    Narrative: CLIMBING TO 16,000' ENROUTE SAT-HOU. NORMALLY CLRD TO FL250 AFTER INITIAL CONTACT WITH CENTER. DUE TO SLOWER TFC, THAT WAS ALSO CLIMBING AHEAD, WE WERE BEING STEP CLIMBED IN 1000' INCREMENTS. AUTOPLT WAS ENGAGED WITH F/O FLYING. I CALLED 15,000 FOR 16,000 AND OBSERVED THE AUTO CAPTURE WAS ARMED. AT 15,700 I WAS DISTRACTED BY A CALL ON THE COMPANY RADIO. ALT ALERT SOUNDED AT 16,300. I DISCONNECTED THE AUTOPLT AND RETURNED TO 16,000. 16,400 REACHED BEFORE CLIMB COULD BE STOPPED. SEVERAL SECONDS AFTER THIS OCCURRED CENTER CLRD US TO FL180 AND I ASSUME NO CONFLICT OCCURRED. WE HAD PASSED THE SLOWER TFC. CONCLUSIONS: SUSPECT THE F/O HAD DISARMED THE AUTOCAPTURE BY MOVING THE VERTICAL SPEED WHEEL. IT IS NOT UNCOMMON FOR F/O'S TO DISARM THE ALT CAPTURE BY MOVING THE VERTICAL SPEED WHEEL, BUT IN THIS CASE I THOUGHT HE WOULD NOT, DUE TO HIS EXPERIENCE AND PREVIOUS PERFORMANCE. I SHOULD NOT HAVE ALLOWED MYSELF TO BE DISTRACTED DURING THIS CRITICAL PHASE OF FLIGHT, AND RELIED ON THE F/O. SUPPLEMENTAL INFO FROM ACN 51098: AS WE WERE CLIMBING THE CAPT AND I DISCUSSED THE FACT THAT THIS WAS ONE AREA OF FLYING THAT REQUIRED INCREASED CARE DUE TO THE FACT THAT WITH EACH LEVEL OFF THERE WAS THE OPPORTUNITY TO FLY THROUGH THE ASSIGNED ALT WITH CLOSE CONFLICTING TFC. AS WE WERE RETURNING TO 16,000' THE CTLR GAVE A NEW CLRNC TO FL230. I DO NOT BELIEVE THAT THERE WAS A TFC CONFLICT DUE TO OUR HIGH OVERTAKE SPEED AND THE CLRNC TO 230 WITHIN SECONDS OF OUR NOTICING THE FAILURE TO LEVEL OFF. I WAS EXTREMELY DISPLEASED WITH MYSELF FOR NOT NOTICING THE FAILURE TO LEVEL OFF WITHIN MINUTES OF DISCUSSING THE VERY EVENT. THE ACFT WITH ADVANCED FLIGHT GUIDANCE DO SUCH A SMOOTH JOB OF FLYING THAT CAPTURE OF ALT ARE NOT FELT AS IN EARLIER ACFT AND WHEN THE FLIGHT GUIDANCE FAILS TO GO TO ALT HOLD IF A PERSON IS AT ALL DISTRACTED IT IS VERY EASY TO MISS THE FACT UNTIL THE ALT ALERTER GOES OFF. IT WOULD HELP IF THE ALT ALERTER WOULD GO OFF AT 150' OR 200' FROM ASSIGNED ALT INSTEAD OF 300' (THE SAME DISPLACEMENT NEEDED FOR VIOLATIONS). ALSO IN TRAINING, INCREASED EMPHASIS SHOULD BE PLACED ON COCKPIT MANAGEMENT AND HANDLING DISTRACTIONS FROM BOTH OUTSIDE AND INSIDE OF THE COCKPIT.

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  4. Accession Number: 60729
    Synopsis: UNDETECTED CANCELLATION OF ALT CAPTURE MODE ON FLT GUIDANCE SYSTEM RESULTED IN ALT OVERSHOT.
    Narrative: I WAS ON MY INITIAL LINE OPERATING EXPERIENCE AS A FIRST OFFICER WITH A COMPANY CHECK AIRMAN, FLT INSTRUCTOR. WE WERE CLEARED FOR TAKEOFF TO CLIMB AND MAINTAIN 5000' MSL. THE AUTOPILOT WAS ENGAGED AT 1000 AGL AND THE FGS (FLT GUIDANCE SYSTEM) WAS ARMED FOR 5000' MSL ALT CAPTURE. OUR PROCEDURES CALL FOR SELECTING IAS (INDICATED AIRSPEED) MODE FOR CLIMB ONCE REACHING OUR MINIMUM MANEUVERING SPEED. WE REACHED MINIMUM MANEUVERING AT APPROXIMATELY 3800' MSL. AT THAT POINT THE FGS HAD ALREADY GONE INTO THE ALT CAPTURE MODE BECAUSE OF OUR HIGH VERTICAL SPEED (APPROX 3500 FPM). WHEN I SELECTED IAS AT 3800' MSL I DID NOT CATCH THE FACT THAT THE FGS WAS ALREADY IN THE ALT CAPTURE MODE, AND BY SELECTING IAS I CANCELLED OR DISARMED THE ALT CAPTURE AND HOLD MODE FOR 5000' MSL. OUT OF 5200' MSL THE AURAL WARNING FOR ALT WENT OFF INDICATING WE HAD EXCEEDED 5000' MSL. NEITHER THE CHECK AIRMAN NOR MYSELF KNEW OF THE PROBLEM UNTIL THE AURAL WARNING SOUNDED. THE AUTOPILOT WAS IMMEDIATELY DISENGAGED AND THE NOSE LOWERED TO GO BACK TO 5000' MSL. I BELIEVE THE CLIMB WAS STOPPED ABOUT 5500' TO 5600' MSL. WE IMMEDIATELY RETURNED TO 5000' MSL.

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  6. Accession Number: 68232
    Synopsis: MLG DESCENDING TO FL240 DESCENDED TO FL233 BEFORE IT WAS RETURNED TO ASSIGNED ALT.
    Narrative: CLEARED BY MEMPHIS CENTER TO DESCEND TO FL240. F/O FLYING WITH AUTOPLT ENGAGED. TRANSIENT ABERRATION IN WING DEICE CYCLE, CAPT WAS LOOKING FOR APPROPRIATE CIRCUIT BREAKER. ALT ALERT SOUNDED AND ALT NOTED AS FL236. LOWEST ALT WAS FL233. ACFT WAS PROMPTLY RECOVERED TO FL240. NO KNOWN TRAFFIC CONFLICT. TWO MAN CREW, ONE DISTRACTED BY MINOR MECHANICAL DISCREPANCY AND OTHER ATTEMPTING TO COMPLY WITH CROSSING RESTRICTION AND AIRSPEED CHANGE. AFTER DISCUSSING INCIDENT I'M CONVINCED IN EFFORT TO COMPLY WITH SPEED CHANGE F/O MOVED IAS CONTROL WHEEL WHILE IN ALT CAPTURE PHASE, CAUSING ARMED ALT TO 'DROP OFF'. COMMON GLITCH WITH THIS AUTOPLT SYSTEM. WE'RE ALL AWARE OF IT, BUT IT CONTINUES TO CATCH US OCCASIONALLY.

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  8. Accession Number: 69140
    Synopsis: ACR MLG ALT DEVIATION OVERSHOT DURING DESCENT FROM CRUISE ALT.
    Narrative: ON DESCENT FROM 35000 INTO SEATAC FROM BOISE RECEIVED CLRNC TO FL180 FROM PREVIOUSLY ISSUED FL240. DURING DESCENT RECEIVED A SPEED REDUCTION FOR SEQUENCING. THE MLG (OUR ACFT) WAS BEING FLOWN BY THE COPLT WITH AUTOPLT (AP) AND AUTO THROTTLES ENGAGED. THE ALT SELECT MODE WAS ARMED. THE AP MODE USED WAS VERTICAL SPEED WHICH IS A MODE WHICH CAN DELETE THE ALT CAPTURE FEATURE IF THE VERTICAL SPEED IS ADJUSTED WITHIN A VARIABLE CAPTURE ZONE. THIS ZONE VARIES DEPENDING ON A NUMBER OF FACTORS. THE ALT ALERT FUNCTIONS AURALLY ONLY AFTER 300' DEVIATION. APPARENTLY BOTH I AND COPLT WERE DISTRACTED WHEN AN ADJUSTMENT OF VERTICAL SPEED DELETED SELECTED ALT CAPTURE. THE AURAL WARNING FUNCTIONED AT 17700' AND WE REACHED 17500' PRIOR TO CORRECTING TO FL180. AN EXCUSE?? YES, BUT ALSO A DESIGN DEFICIENCY. THE AURAL WARNING SHOULD BE PRIOR TO ALT DEVIATION NOT AFTER. THE AP MODE SHOULD NOT ALLOW DELETION OF SELECTED CAPTURE ALTS IN SOME CIRCUMSTANCES AND NOT OTHERS. NO TRAFFIC CONFLICT RESULTED NOR DID ATC MAKE MENTION OF THE DEVIATION.

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  10. Accession Number: 73941
    Synopsis: ACR MLG HAD ALT EXCURSION.
    Narrative: THE FLT HAD DEPARTED RDU ENRTE ORD. LEVEL OFF AT CRUISE ALT WAS NORMAL WITH THE AUTOPLT ENGAGED IN THE PERFORMANCE MODE FOR BOTH THE CLIMB AND CRUISE. ABOUT 15 MINS AFTER LEVEL OFF THE ALT ALERT SOUNDED. THE ALT HOLD MODE BUTTON WAS IMMEDIATELY PUSHED WHICH STOPPED THE CLIMB AT 250' ABOVE THE ASSIGNED ALT. THE ACFT WAS DESCENDED BACK TO FL330. THE REMAINDER OF THE FLT WAS NORMAL. THIS TYPE ACFT DURING CRUISE USING THE "PERF" MODE MAINTAINS SPEED BY INCREASING AND DECREASING THE PITCH WHICH RESULTS IN A VERTICAL SPEED UP AND DOWN OF JUST A FEW FEET (20) TO AS MUCH AS 120 FPM. FOR SOME UNKNOWN REASON THE ALT HOLD TRIPPED OFF AND THE ACFT DRIFTED OFF ALT AT THE VERTICAL SPEED EXISTING AT THE TIME OF THE ALT HOLD TRIP OFF. THIS IS THE THIRD TIME THIS HAS HAPPENED ON THIS TYPE OF ACFT IN THE PAST 90 DAYS, ON AN ACFT I'VE BEEN A CREW MEMBER WORKING. IT WOULD BE A GREAT HELP IF THERE WAS AN AURAL WARNING OF SOME KIND PROGRAMMED INTO THE SYSTEM TO ALERT THE CREW THAT THE AUTOPLT/FLT DIRECTOR HAS CHANGED TO A MODE OF OPERATION OTHER THAN THAT WHICH WAS SELECTED AND OPERATING. THIS TYPE OF TRIP OFF IS VERY INSIDIOUS. THE FLT MODE ANNUNCIATOR DOES CHANGE BUT ONE WOULD HAVE TO BE LOOKING AT IT TO CATCH IT IMMEDIATELY.

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  12. Accession Number: 77914
    Synopsis: ALT OVERSHOT ON CLIMBOUT WHEN DESCENT CLRNC WITH ALT RESTRICTION GIVEN BEFORE REACHING ASSIGNED ALT AND FMC REPROGRAMMED.
    Narrative: WE HAD RECEIVED A CLRNC TO CLB TO 16000', DIR TO THE SRP VORTAC ON THE 23 MIN FLT FROM TUS TO PHX. SOMEWHERE BTWN 11000' AND 15000' (SLIGHTLY LESS THAN 1 MIN'S TIME) WE WERE CLRD TO CROSS 35 SE OF SRP AT OR BELOW 14000', 250 KTS, MAINTAIN 10000'. AS IS STANDARD PRACTICE AT OUR COMPANY, I SET THE NEW CLRNC LIMIT ALT (10000') IN THE ALT SELECTOR OF THE AUTOPLT/FLT DIRECTOR SYSTEM MODE CTL PANEL, MENTALLY ASSURING MYSELF THAT THE AUTOPLT WOULD LEVEL THE ACFT AT 16000' SINCE THAT WAS THE CRS ALT PROGRAMMED IN THE FLT MANAGEMENT COMPUTER (FMC). I REACHED INTO MY FLT BAG TO PULL OUT A BINDER TO STOW MY TUCSON PLATES, AND WAS JUST OPENING IT WHEN THE ABQ CENTER CTLR CALLED, "PHX ALTIMETER 29.84." I RESET THE ALTIMETER AND NOTED THAT THE INDICATED ALT WAS NOW 16400' AND CLBING RAPIDLY. I DISCONNECTED THE AUTOPLT AND MANUALLY LEVELED AT 16000'. THE MAX INDICATED ALT WAS 16700'. COMMON PRACTICES CAN LEAD TO CRITICAL ERRORS UNDER SITUATIONS ONLY SLIGHTLY DIFFERENT FROM THE NORM. NORMALLY, WE DON'T RECEIVE DES CLRNCS BEFORE REACHING THE ASSIGNED CRS ALT. NORMALLY, WE SET THE ALT SELECTOR OR ALERTER TO THE NEW CLRNC LIMIT ALT AS SOON AS WE RECEIVE IT. I DID THIS AUTOMATICALLY W/O CONSIDERING THAT IT MIGHT BE AN INVALID RESPONSE. WE'RE PSYCHOLOGICALLY PROGRAMMED TO EXPECT THINGS TO HAPPEN WITH A MACHINE BASED ON OUR EXPERIENCE WITH WHAT USUALLY HAPPENS. WITH THIS AIRPLANE'S EFIS DURING A CLB OR DES IN THE VNAV MODE, THE AIRPLANE WILL LEVEL OFF AT THE CRS ALT PROGRAMMED IN THE FMC EVEN IF THE ALT SELECTOR IS SET AT A HIGHER (DURING CLB) OR LOWER (DURING DES) ALT. EX: FMC CRS ALT FL330, CLRD TO FL370, ALT SELECTOR SET TO 370, AUTOPLT LEVELS THE AIRPLANE AT FL330. HAPPENS ALL THE TIME, SO I KNEW THE AUTOPLT WOULD LEVEL THE ACFT AT 16000'. WRONG! WHAT I DID, IN FACT, WAS TELL IT TO STOP AT AN ALT I WASN'T ON THE WAY TO. THE AUTOPLT THEN REVERTED TO THE CWS PITCH MODE, IN WHICH THE AIRPLANE KEEPS ON GOING IN THE LAST DIRECTION IT WAS POINTED, UNTIL THE PLT POINTS IT SOMEWHERE ELSE WITH THE YOKE. THERE IS NO AURAL WARNING WHEN THIS HAPPENS, THE AUTOPLT HASN'T DISCONNECTED, IT'S JUST HLDG A PITCH ATTITUDE. THERE'S A SMALL YELLOW CWS PITCH WARNING ON THE EADI, BUT IT HAS TO BE LOOKED AT TO BE SEEN (MUCH LIKE TFC AND ALTIMETERS). I ALSO KNEW I'D HAVE TIME TO STOW MY DEP PLATES BEFORE APCHING 16000', AS THE AUTOPLT STARTS A SMOOTH LEVEL OFF AS A FUNCTION OF RATE OF CLB AND WOULD BE REDUCING IT'S RATE OUT OF ABOUT 13000'. WRONG AGAIN! SINCE IT DEFAULTED TO CWS PITCH AND I DIDN'T NOTICE IT, WE WERE STILL CLBING AT 4 TO 6000 FPM. NO TIME FOR ANY INATTN OR DISTR. SO WHERE WAS THE NFP WHO WOULD NORMALLY BE CROSSCHECKING ALT AND MAKING APPROPRIATE CALLOUTS? THE SAME PLACE HE ALWAYS IS DURING MOST OF THE TIME SPENT ABV 10000' ON THIS RUN: DEEP IN THE MIDDLE OF COPYING ATIS AND MAKING REQUIRED FLT-FOLLOWING RADIO CALLS TO THE COMPANY. IT'S COMMON KNOWLEDGE THAT THE PF HAS LITTLE BACKUP ON A SHORT FLT LIKE THIS, BECAUSE THERE IS SO MUCH RADIO WORK TO DO. ALL THE MORE REASON FOR THE PF TO DO NOTHING BUT FLY (OR, THESE DAYS, MONITOR). SOMEWHERE IN ABQ CTR THERE WAS AN ALERT CTLR WHO TACTFULLY BROUGHT MY ATTN BACK WHERE IT SHOULD HAVE BEEN IN THE FIRST PLACE. MY HAT IS OFF TO HER! THE NEW TECHNOLOGY MACHINERY (FMC, EFIS, ETC) IS MARVELOUS, BUT IT SUCKERS US INTO COMPLACENCY. IN THE OLDER SERIES AUTOPLT, THE CWS MODE WAS THE NORM, RATHER THAT THE EXCEPTION. THIS WAS FINE, AS YOU KNEW YOU WERE IN IT. IN MY EXPERIENCE, THERE'S A MUCH HIGHER INCIDENCE OF ALT/SPD/ROUTE BUSTS IN THE FMC-EQUIPPED ACFT, LARGELY (I THINK) BECAUSE THE SYSTEM IS SO COMPLEX THAT THERE ARE MANY OPPORTUNITIES FOR FAULTY PROGRAMMING. SUGGESTIONS: ALT AWARENESS! ALT ALERTERS ARE WONDERFUL, BUT WE'VE BECOME TOO DEPENDENT ON THEM. LET'S ALL TAKE A HARD LOOK AT OUR PROCS FOR THEIR USE AND BE SURE THEY'RE VALID FOR THE INTENDED RESULT. CONTINUALLY EMPHASIZE THE IMPORTANCE OF DEVOTING YOUR FULL ATTN TO MONITORING THE FLT WHENEVER THE OTHER CREWMEMBERS ARE INVOLVED WITH OTHER DUTIES. TRY TO MINIMIZE DISTRS DURING CLBS/DES, NOT JUST BELOW 10000'. ALWAYS FOLLOW UP ANY CHANGES IN AUTOPLT/FLT DIRECTOR MODE WITH A CHK OF THE MODE ANNUNCIATOR. IN NEW TECHNOLOGY ACFT, THIS MEANS EVERY TIME YOU PUSH A BUTTON. FOR R & D: IF WE MUST HAVE AN AURAL WARNING FOR AN AUTOPLT DISCONNECT, IS IT ANY LESS DANGEROUS TO HAVE IT REVERT TO A CWS MODE W/O THE PLT BEING AWARE? THIS IS A VERY COMMON OCCURRENCE. A CANCELLABLE AURAL WARNING AFTER, SAY, 3 SECS OF CWS WOULD DO THE TRICK. PERHAPS IF THE MACHINE CAN LEAD US ASTRAY, IT SHOULD WARN US. IS IT ACCEPTED PRACTICE FOR ATC TO GIVE DES CLRNCS PRIOR TO REACHING THE ASSIGNED CRS ALT? THIS COULD LEAD TO VARIOUS ERRORS AND CONFUSION.

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  14. Accession Number: 82955
    Synopsis: ACR MLG OVERSHOT ALT DESCENT DUE TO AUTOPLT MALFUNCTION.
    Narrative: ALTIMETERS SET CORRECTLY TO LCL SETTING. DSNDING TO 10000' MSL AT 250 KIAS. ACFT IS MLG. ALT IS ARMED AT 10000', SPD SELECT AT 250 KTS. WHEN ACFT IS ABOUT TO LEVEL AT 10000' MSL FLT GUIDANCE SUDDENLY GOES INTO VERT SPD AT ABOUT 2100' DESCENDED. I IMMEDIATELY PRESSED ALT HOLD 2 OR 3 TIMES, BUT HAD NO EFFECT. DISCONNECTED AUTOPLT AND MANUALLY FLEW BACK TO 10000' MSL. ALT DEVIATION WAS 250-300' DOWN FROM 10000'. ALT VOICE FROM CAWS WAS HEARD AND ALSO ALT LIGHT ON ALTIMETER ILLUMINATED. REASON FOR EXCURSION UNKNOWN. FLT GUIDANCE SYS JUST HAD A MIND OF ITS OWN. PLT WAS NOT TOUCHING ANYTHING WHEN EXCURSION STARTED. SYS WAS SET PROPERLY AND ALT ARMED.

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  16. Accession Number: 92507
    Synopsis: ACR MLG ALT DEVIATION EXCURSION FROM CLRNC ALT. REPORTER SAYS FMA CHANGED FLT MODE AND ALT SELECT BY ITSELF.
    Narrative: THE F/O WAS FLYING THE ACFT. WE HAD BEEN ISSUED SEVERAL VECTORS AND TURNS BY ATC FOR FLOW CTL INTO CHICAGO O'HARE. I WAS ON THE P/A EXPLAINING THE ENRTE DELAY TO THE PAX WHEN I NOTICED THE FMA HAD CHANGED FROM "PERF CRUISE" TO "PERF DSNT," AND THE ALT SELECT HAD CHANGED FROM 35000 TO 33000'. I ASKED THE F/O IF WE HAD BEEN CLRED TO FL330. HE SAID NO. THE ACFT ALT WAS 34600' WHEN I NOTICED THE PROB. THE DSNT WAS STOPPED AT 34500'. I DON'T KNOW WHY THE AUTOPLT ENTERED A DSNT MODE. AN ALT WARNING DIDN'T OCCUR BECAUSE THE ALT SELECT HAD CHANGED ALSO. I SUSPECT A PWR SURGE IN THE ELECTRICAL SYS MAY HAVE CAUSED THE PROB. I HAVE EXPERIENCED THIS PROB IN THE PAST WITH THE MLG FLT GUIDANCE SYS WHEN A HYD PUMP IS TURNED FROM LOW TO HIGH.

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  18. Accession Number: 103884
    Synopsis: ACR LGT GETS INTO APCH TO STALL AND ALT EXCURSION WHEN AUTO THROTTLES DO NOT MAINTAIN SPEED.
    Narrative: DSNDED FROM FL410 OT ASSIGNED FL240 WITH CLRNC TO HOLD AT BUNKER INTXN ENRTE TO MSP. USED VERT SPD AND SPD INTERVENE ON MODE CONTROL PANEL. MSP ATC REQUESTED WE LEVEL AT FL330. WE DID SO. WE GOT ALT CAPTURE AND I WAS SATISFIED WE WERE AT FL330 AND CHKED AIRSPD. I WAS SATISFIED THAT IT WAS AT 220 KTS AS I HAD SELECTED. I THEN PROCEEDED TO VERIFY THAT THE FMC WAS PROPERLY PROGRAMMED TO HOLD AT BUNKER INTXN AS DIRECTED. WHILE CHKING FMC WE EXPERIENCED THE STICK SHAKER. I MANUALLY WENT TO FULL PWR AND NOTED AIRSPD TO BE QUITE LOW, APPROX 140 KTS. I TOOK ACFT OFF THE AUTOPLT AND PROCEEDED TO FLY THE ACFT OUT OF THE PENDING STALL. WE LOST 300-400' OF ALT AND COPLT INFORMED MSP ATC WE WERE OFF ALT AND CORRECTING. MSP ATC CLRED FLT TO FL290 AT THAT TIME AND WE PROCEEDED TO COMPLETE AIRSPD CORRECTION DURING OUR DSNT TO FL290. WE HAD 2 MORE DSNTS WHILE HOLDING AND WE TRIED TO RECREATE THE CIRCUMSTANCES THAT LED TO THE LOST OF AIRSPD PROB. THE ACFT AND SYSTEMS SEEMED TO FUNCTION NORMALLY. MY PERSONAL EVALUATION IS: THAT WHILE I WAS IN SPD INTERVENTION ON THE MODE CONTROL PANEL DURING THE INITIAL DSNT PHASE THE ACFT ENDED UP NOT BEING IN A SPD MODE WHEN WE LEVELED OFF AT FL330. THE ACFT SYS RESPONDED TO COMMANDS DURING DSNT FROM FL410, BUT FAILED TO MAINTAIN SELECTED AIRSPD WHEN AT FL330. SELECTED MODES WERE NOT CHANGED. ALT CAPTURE/ALT HOLD WAS VERIFIED. I REMAINED IN SPD INTERVENE AND CONSCIOUSLY VERIFIED AIRSPD INDICATOR ON THE SALMON AIRSPD BUG PRIOR TO SHIFTING MY ATTN TO THE FMC PANEL TO CHK HOLDING PROGRAMMING. I VISUALLY CHKED ALT CAPTURE/ALT HOLD ON PITCH MODE STATUS ON ADI. THOUGH I CHKED AIRSPD INTERVENE, AIRSPD INDICATOR, SALMONBUG, AND GENERAL COCKPIT ENVIRONMENT, I CANNOT ACTUALLY REMEMBER CHKING THE AUTOTHROTTLE STATUS/MODE ON THE SAME PRIMARY ADI INSTRUMENT WHEN I CHKED ALT CAPTURE/ALT HOLD. THAT THE PRESTALL STICK SHAKER IS A VALUABLE ASSIST TO SAFETY. THAT I, THE PF, FAILED TO PROPERLY MONITOR THE FLT INSTRUMENTS. THAT HOW THE ACFT GOT OUT OF SPD MODE IS NOT KNOWN TO ME. SUPPLEMENTAL INFO FROM ACN 103889: IN CLOSING DUE TO THE HIGH WORKLOAD IN THE COCKPIT (CAPT WAS REVIEWING THE HOLDING PATTERN AND I WAS PROGRAMMING THE COMPUTER) WE ALLOWED THE AUTOMATION TO FLY THE ACFT. THE CAPT HAD ENSURED THAT THE ACFT LEVELED PRIOR TO REVIEWING THE HOLD. AUTOTHROTTLES DID NOT ENGAGE AND SPD DECREASED TO STICK SHAKER.

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  20. Accession Number: 146839
    Synopsis: ACR MLG ALT DEVIATION ALT UNDERSHOT. ALT CROSSING RESTRICTION NOT MET.
    Narrative: FLT 5/90, CLT-SFO, DSNDING INTO SFO WBND TO MOD VOR. BEING VECTORED AND ASSIGNED 250 KIAS, GIVEN LOCKE ARR TO SFO, WE FOUND THAT THE LOCKE ARR IS NOT IN OUR RNAV/FMC DATA BASE. WHILE BLDG THE ARR INTO FMC (WITH F/O READING DATA AND CAPT INPUTTING FMC) FOUND ACFT NO LONGER IN AUTOTHROTTLE SPD MODE, AND AIRSPD UP TO 290 KIAS. BEGAN REDUCING BACK TO 250 KTS AS CTLR ASKED ABOUT OUR SPD. CONTINUED DSNT W OF MODESTO IN FMC VNAV MODE WITH CLRNC TO CROSS LOCKE INTXN AT 10000'. CTLR ASKED US DURING DSNT IF WE WOULD MAKE THE RESTRICTION; F/O AFFIRMED WE WOULD. A MINUTE OR SO LATER I TOLD F/O TO TUNE IN SCAGGS ISLE VORTAC AND VERIFY OUR POS. WE FOUND WE WERE AT LOCKE, NOT THE 10-12 MI SE SHOWN BY FMC. CTLR THEN TOLD US WE WERE AT LOCKE. OUR ALT WAS APPROX 14000'. I ACKNOWLEDGED OUR ERROR ON THE RADIO AND EXTENDED THE SPD BRAKES, HURRYING DOWN TO 10000'. AFTER STABILIZED AT 10000', I HAD THE F/O CHK THE POS WE HAD PUT INTO THE FMC FOR LOCKE. WE FOUND THAT HE HAD GIVEN ME THE DISTANCE FROM UPEND TO LOCKE, RATHER THAN THE MILEAGE OF LOCKE FROM SCAGGS ISLE VORTAC. RECOMMENDATIONS: AIRLINE SHOULD PROVIDE COMPLETE DATA BASE IN RNAV (FMC). WHEN NECESSARY TO BUILD DATE, ONE PLT BUILDS INTO FMC WHILE OTHER MONITORS ACFT. SECOND PLT THEN VERIFIED VALIDITY OF NEW DATA BY CHKING LAT/LONG COORDINATES BEFORE DATA IS ACTIVATED. USE VORTAC BACKUP AS SOON AS ALT RESTRICTIONS ARE ISSUED. SUPPLEMENTAL INFO FROM ACN 146837: COCKPIT WORKLOAD WX, SB AM, WALKUP CALL TO START THIS TRIP.

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  22. Accession Number: 156414
    Synopsis: ACR MLG STRAYS OFF AIRWAY AS FMCGOES TO A DEAD RECKONING MODE. ALERT CTLR INQUIRES ABOUTDEVIATION.
    Narrative: WE WERE NAVIGATING USING THE FMS"MAP" MODE ON ELECTRONIC INSTRUMENT DISPLAYS (GLASS COCKPIT). AS WE APCHED MOL NAVAID, SYS ANNUNCIATION SHOWED "D/R" (DEADRECKONING) INDICATING THAT WE HAD LOST NAV STATION UPDATES TOFMS AHRS (ALT HDG REFERENCE SYS). ABOUT SAME TIME ATC CALLED ANDASKED US IF WE WERE SHOWING ON ARWY BECAUSE HE SHOWED US ABOUT 8NM N OF COURSE. WHEN WE SWITCHED TO "ARC" DISPLAY TO SHOW NAV RINFO IT TOO SHOWED US "OFF COURSE". EVIDENTLY FMS SYS WASWORKING WITH ERRONEOUS XWIND OF 350/101. WHEN WE SELECTED"PROGRESS PAGE" OF FMS IT SHOWED NO NAVAIDS IN USE, THE SYS WAS"LOST". WE RESET OUR PRESENT POS (USING NAVAID AND DME) ON FMSPOS PAGE. FMS REESTABLISHED (AND FOUND) ITSELF AND WE REGAINEDFMS NAV GUIDANCE. EVEN THOUGH WE PERIODICALLY XCHKED FMS NAVDATA. IT CAUGHT US OFF OUR GUARD.

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  24. Accession Number: 158189
    Synopsis: ACR MLG ALT DEVIATION OVERSHOTDURING DESCENT. FLT CREW CLAIMS THEY SET 240 IN ALT ALERT, BUTAPPROX 1 MINUTE LATER IT READ 210.
    Narrative: INBND TO FILLMORE VOR FROM THE EWITH AUTOFLT ENGAGED, ACFT WAS DSNDING FROM 35000' WITHINTERMEDIATE LEVEL-OFFS, FOR A PLANNED LNDG AT SBA. IN LEVEL FLTAT 28000' ACFT WAS CLRED TO MAINTAIN 24000'. CLRNC WASACKNOWLEDGED AND NEW ALT SET IN MCP ALT SET WINDOW AND CHKED BYBOTH PLTS. LEVEL CHANGE WAS SELECTED ON MCP (AN AUTOPLT DSNTMODE) AND ACFT STARTED DOWN AT APPROX 3000 FPM. AT APPROX 26000'PNF CHKED OFF (WITH PF CONCURRENCE) FROM MONITORING ATC TOLISTEN TO SBA ATIS. TIME OFF ATC FREQ APPROX 1 MIN. AT APPROX24000' PF RECEIVED FREQ CHANGE FROM ZLA AND WHEN CHKING IN WITHNEW CTLR, RPTED PASSING APPROX 23000 FOR 21000'-- 21000' BEINGTHE ALT SHOWING IN THE MCP ALT WINDOW, HOWEVER NOT SET BY EITHERPLT. CTLR ACKNOWLEDGED XMISSION THEN REQUESTED LAST ALT CLRNC.PF ONCE AGAIN RESPONDED "FL210," BECAUSE THAT WAS THE ALT SET INMCP ALT WINDOW. CTLR ACKNOWLEDGED XMISSION AND SUBSEQUENTLYCLRED ACFT TO MAINTAIN FL220. PROB AREA: PNF OUT OF LOOP FORAPPROX 1 MIN WHILE OBTAINING ATIS WHICH WAS WORTH 3000' OF ALTLOS. PF ACCEPTED ALT SET IN MCP WINDOW AS CORRECT ALT FRO LASTCLRNC. UNCOMMANDED ALT CHANGE IN ELECTRONIC ALT SET WINDOW DUESOFTWARE PROB? CORRECTIVE ACTION: GREATER DILIGENCE ON PART OFPLTS, ESPECIALLY WHEN ONLY 1I FLYING AND COMMUNICATING.UNCOMMANDED ALT CHANGE IS RECURRING PROB IN GLASS COCKPIT--NEEDCHANGE IN SOFTWARE OF INSTALL A MORE TRADITIONAL ALT SET WINDOW.

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  26. Accession Number: 192224
    Synopsis: ACR MLG ALTDEV EXCURSION FROM CLRNC ALT THEN ALT OVERSHOOT WHEN RETURNING TO CLRNC ALT. ALL WITH THE 'HELP' OF FMC AND AUTOPLT.
    Narrative: MLG WITH FMC-EFIS DSNDING INTO SFO FROM IAH. CAPT FLYING, FO PERFORMING ALL OTHER PNF DUTIES. ACFT JUST LEVELED AT 240 AFTER DSCNT FROM FL280. FO 'OFF THE AIR' GIVING FINAL PA ANNOUNCEMENT TO PAX. UPON RETURNING TO THE FREQ, FO HEARD CAPT ACKNOWLEDGE ATC TRANSMISSION FOR CLRNC TO 11000 FT. AUTOPLT WAS ENGAGED THROUGHOUT ENTIRE FLT WITH NAV AND LNAV MODES ENGAGED. UPON CLRNC TO 11000 FT, CAPT POINTS TO ALT SELECTOR WINDOW AND FO SELECTS 11000. THEN FOLLOWED A BRIEF DISCUSSION AS TO FACT THAT FL240 SHOULD BE MAINTAINED UNTIL PASSING A FIX ABOUT 3 MI IN FRONT OF ACFT AT WHICH POINT FO SELECTS FL240 ON ALT SELECTOR ALTHOUGH MOMENTARILY OVERSHOOTING SELECTED ALT TO FL250. DURING THIS TIME, ACFT HAD BEGUN DSCNT FROM FL240 TO ABOUT FL236 AT WHICH TIME AIRSPD DROPPED ABRUPTLY FROM 280 KIAS TO 210 KIAS AND NOSE PITCHED SHARPLY UP TO 15 DEG. ACFT BEGAN RAPID CLB OF ABOUT 2500-3000 FPM AND REACHED 24800 FT, BY THE TIME CAPT DISCONNECTED THE AUTOPLT TO LEVEL ACFT AND BEGIN DSCNT TO APPROPRIATE ALT. THE CAUSE OF THIS UNCOMMANDED CLB WAS NEVER DETERMINED BY CREW AND DID NOT RESULT IN ANY TFC CONFLICT TO OUR KNOWLEDGE. TAKING INTO ACCOUNT THE COMPLEXITY OF THE MLG FMC AND ITS ABILITY TO REVERT AUTOMATICALLY FROM ONE MODE TO ANOTHER AS WELL AS THE HIGH COCKPIT WORKLOAD AT THIS POINT, ONE HAS NO TIME TO TRY AND DIAGNOSE THE REASON BEHIND AN UNWANTED AUTOPLT ACTION AND DISCONNECTION IS THE ONLY PRUDENT ACTION.

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  28. Accession Number: 192414
    Synopsis: ACR CREW EXCEEDS MAX AIRSPD. AUTOPLT DISENGAGES, ACFT CLBS.
    Narrative: AFTER LEVEL OFF AT CRUISE ALT FL290, THE PF BECAME DISTRACTED AND DID NOT REDUCE PWR FROM CLB TO CRUISE THRUST. CONSEQUENTLY, AIRSPD ACCELERATED TO MMO, ABOUT .81 MACH. THE 'MAX AIRSPD' LIMITING FEATURE OF THE AUTOPLT THEN ENGAGED ITSELF, DISENGAGING ALT HOLD, AND THE AIRPLANE BEGAN A SLOW CLB. I NOTICED THIS BTWN 29200 AND 29300, AND IMMEDIATELY SLOWED AND DSNDED THE ACFT BACK TO FL290. THE ATC CTLR SAID NOTHING SO I GUESS THERE WAS NO CONFLICT. FURTHER TO THIS, I CALLED THE AREA MGR AT LAX CENTER AND HE SAID HE HAD NO RPTS. THIS WAS A PLT ERROR. IT WOULD HAVE BEEN HELPFUL IF THE AUTOPLT WAS DESIGNED TO GIVE THE PLTS AN AURAL WARNING WHEN DISENGAGING ITSELF FROM ALT HOLD TO MAINTAIN VMO OR MMO. THERE IS AN MMO CLACKER BUT THE AUTOPLT SPD LIMITER TOOK OVER TOO SOON!

  29.  
  30. Accession Number: 360828
    Synopsis: ALTDEV ALT UNDERSHOOT. AUTOPLT AUTOCAPTURE REVERTED TO VERT SPD MODE.
    Narrative: ATC CLRED FLT TO 12000 FT AT CROWE, THEN SUBSEQUENTLY LIMITED THAT TO 21000 FT WHILE ISSUING A VECTOR N. ACFT HAD BEEN SPED UP, SLOWED DOWN AND GIVEN NORMAL SPD PRIOR TO THIS, CAUSING THE AUTOMATION TO BE A HINDRANCE TO OPS AND TRIPPING TO VERT SPD. ACFT DID NOT AUTO LEVEL AT 21000 FT -- NOTED BY PLTS AT 20600 FT. WHILE CORRECTING, ATC ADVISED A STEP DSCNT CLRNC TO 20000 FT, THEN 16000 FT, AND FINALLY 12000 FT, 10000 FT, AND VISUAL APCH. NO TFC CONFLICT NOTED. FACTORS: CONSTANT PROGRAMMING CHANGES TO THE FMC, BACKSIDE CLOCK OPS, DISTRACTIONS OF IN RANGE CALLS AND ATC CHANGES TO SPD AND ALT RESTRS THAT INCREASED COCKPIT WORKLOAD IN THE DSCNT PHASE.

  31.  
  32. Accession Number: 361956
    Synopsis: A320 ON GARDNER 2 STAR BOS. CLRED CROSS BRONC INTXN 11000 FT 250 KTS PROGRAMMED. CAPT ADVISED USING RWY 33L. ENTERED LNDG RWY IN FMS AND DID NOT NOTICE THE BRONC RESTR DELETED AND THE ACFT REVERTED TO VERT SPD MODE. CTLR QUESTIONED ALT AND VECTORED FOR FURTHER DSCNT.
    Narrative: DURING DSCNT TO BRONC INTXN TO CROSS AT 11000 FT AND 280 KTS, THE CAPT WAS GETTING WX ON THE OTHER RADIO AND I ENTERED THE LNDG RWY 33L INTO THE FMS. THIS CAUSED THE RESTR AT BRONC (280 KTS/11000 FT) TO DELETE ITSELF. I HAD THE ACFT SELECTED TO MANAGED FLT AND DID NOT OBSERVE THAT IT CHANGED TO VERT SPD AND THE RESTR DELETED. CTR REALIZED THAT WE PROBABLY WOULD NOT MAKE THE RESTR AND GAVE US A VECTOR. NO OTHER TFC OR CONFLICTS. THIS WOULD NOT OCCUR IF ONCE A RESTR WAS PLT ENTERED INTO THE FMS IT WOULD NOT AUTOMATICALLY DELETE ITSELF WHEN A DEST RWY IS ENTERED. A PLT ENTERED RESTR SHOULD ONLY BE DELETED BY PLTS, NOT THE FMS. ESPECIALLY SINCE THE ARPT IS 39 NM BEYOND THE RESTR AT BRONC INTXN WHICH IS NORMALLY (250 KTS/11000 FT).

  33.  
  34. Accession Number: 364758
    Synopsis: MD88 ON MINKS 1 STAR LGA, CLRED CROSS KERNO INTXN FL260 PLTS DISCRETION. EFIS MAP FAILED AND DSCNT WAS BEGUN. WHEN MAP RESTORED CROSSED KERNO FL285. CTR ADVISED NO PROB.
    Narrative: ON THE MINKS 1 ARR INTO LGA WE WERE GIVEN CLRNC TO CROSS KERNO AT FL260. DISTANCE TO KERNO SHOWED 38 NM SO I DIDN'T START DOWN IMMEDIATELY. CAPT TUNED HIS VOR TO DCA (111.0), FO TUNED COL (115.4) WHICH IS NORMAL PROC. MOMENTS LATER THE EFIS MAP FAILED, FMC TIMED OUT, AND THE AUTOPLT ENTERED THE BASIC MODE. NO DEAD RECKONING WAS DISPLAYED ON PFD. I RE-ENTERED FMS DATA AND STARTED A DSCNT TO FL260. APCHING FL260 THE MAP DISPLAY SHIFTED AND SHOWED US ALMOST ON TOP OF KERNO INTXN. WE CROSSED KERNO AT FL285 AND ZNY CLRED US TO CROSS SOMTO AT 13000 FT. WE QUERIED ZNY AND THEY TOLD US THE HIGH XING WAS 'NOT A PROB.' THE FMC FUNCTIONED NORMALLY FOR THE REMAINDER OF THE FLT.

  35.  
  36. Accession Number: 365320
    Synopsis: FLC OF AN MLG OVERSHOT DSCNT XING RESTR DUE TO MISSET AUTOPLT MODE CTL.
    Narrative: DURING DSCNT WE WERE GIVEN AN ADDITIONAL RESTR TO CROSS HITOP INTXN AT AND MAINTAIN 17000 FT. THIS WAS ENTERED IN LEGS PAGE. I DID NOT, I BELIEVE, RESET MCP ALT TO 17000 FT SINCE I WANTED TO LEVEL AT FL210 TILL WE NEEDED TO GO DOWN TO 17000 FT. WE WERE DSNDING IN VNAV ALL THE TIME WITH THE FOLLOWING ADDITIONAL WAYPOINT RESTRS IN FMC: 1) WHETO AT 12000 FT, AND 2) PSP AT 7000 FT. AS DSCNT CONTINUED, WE ADDED SPD RESTRS TO WHETO AND PSP TO GET SLOWED FOR THE FINAL DSCNT DURING THE EXPECTED VISUAL APCH. AS WE CONTINUED, I CAN'T SAY WHY, BUT I FELT SOMETHING WAS AMISS BUT DID NOT KNOW WHAT AT FIRST AND I STATED THIS TO THE CAPT. THEN I REALIZED WE WERE NEARING HITOP (DON'T RECALL HOW CLOSE WE WERE) AND WERE STILL AT FL210. IT (HITOP) WAS STILL DEFINITELY AHEAD OF US ON MAP DISPLAY. I IMMEDIATELY STATED WE MIGHT NOT MAKE HITOP AT 17000 FT TO THE CAPT, EXTENDED THE SPD BRAKES, WENT TO IDLE THRUST AND MANUALLY DSNDED THE AIRPLANE AS FAST AS POSSIBLE WITHOUT UPSETTING THE PAX. ATC THEN ASKED IF WE'D MAKE HITOP AT 17000 FT, CAPT SAID YES, I BELIEVE. I DON'T RECALL THE ALT AT HITOP BUT WE LEVELED AT 17000 FT PROBABLY 1-2 MI BEYOND. WE WERE, I PRESUME, CLOSE ENOUGH, BUT THE SIT COULD HAVE BEEN WORSE. IN THE END, I THINK OUR DOWNSTREAM WAYPOINT CHANGES CAUSED US TO DROP OUT OF VNAV AND INTO ALT HOLD AT FL210. THIS WOULD EXPLAIN THE LACK OF A 'RESET MCP ALT' MESSAGE PRIOR TO HITOP. THE MORAL OF THE STORY IS TO RECHK AND MONITOR FLT MODE ANNUNCIATIONS AND NEVER ASSUME THAT IT WON'T CHANGE MODES ON YOU WHEN YOU MAKE ALT RESTR MODIFICATIONS. IN THE END, THIS IS SOMETHING I'M QUITE MAD AT MYSELF FOR, FOR NOT MONITORING THE AUTOFLT SYS MORE CLOSELY.

  37.  
  38. Accession Number: 366354
    Synopsis: A320 ACFT ON APCH AND APPARENTLY NOT PROPERLY SET UP FOR THE APCH WAS GIVEN A GAR BY THE APCH CTLR. THE GAR WAS INITIATED, BUT WITHOUT TOGA THRUST UNTIL THE CAPT RPTR TOLD THE FO TO USE TOGA. AT THAT TIME, UNKNOWN TO THE FLC, THE ACFT CHANGED MODES AND IGNORED THE PREVIOUS INPUTS SET INTO THE FMGC.
    Narrative: DUE TO DETERIORATING WX CONDITIONS AND ABNORMALLY HIGH WINDS AT ALT VERSUS ON THE GND, DTW APCH CTL DIRECTED A GAR: MAINTAIN 3000 FT, TURN L 220 DEGS AND SPD OF 170 KTS. I RECOMMENDED TO THE FO TO GO TO THE TOGA THEN BACK TO CLB TO RESEQUENCE THE FMGC FOR THE ADDITIONAL APCH. THE ACFT STARTED CLBING, DISREGARDING THE 3000 FT FCU ALT. I DISCONNECTED THE AUTOPLT AND TOOK CTL OF THE ACFT TO RETURN IT TO 3000 FT. THE FO SAID WATCH YOUR AIRSPD WHICH WAS RAPIDLY INCREASING. THE FMGC IS SUPPOSED TO HONOR THE APCH SPD (140 KTS) OR FCU SELECTED AIRSPD (170 KTS) WHICHEVER IS HIGHER. IT DISREGARDED BOTH. I DISCONNECTED THE AUTOTHRUST AND RETARDED THE THRUST LEVERS. APPARENTLY THE FMGC STUCK IN THE GAR PHASE EVEN THOUGH THE THRUST LEVERS WERE IN THE CLB DSCNT. IN RETROSPECT WHAT WAS UNSETTLING WAS HOW LONG IT TOOK TO RECOGNIZE THE PROB THAN DEAL WITH IT. IN KNOW OUR FMGC'S HAVE BEEN EXPERIENCING NUMEROUS PROBS WHICH HAVE GOTTEN WORSE OVER TIME. I DON'T KNOW IF THIS HAD ANYTHING TO DO WITH THE ABOVE PROB.

  39.  
  40. Accession Number: 373570
    Synopsis: MLG ACFT ON STAR ARR FAILED TO COMMENCE DSCNT TO MAKE XING RESTR DUE TO INADVERTENT DISENGAGE OF VNAV.
    Narrative: ON A FLT FROM SFO TO LAS, APPROX 50 NM W OF BTY, HEADED DIRECT BTY FOR THE FUZZY 4 ARR. I STEPPED BACK TO THE CABIN FOR PERSONAL NEEDS AND UPON RETURNING I NOTICED THE FO HAD SET FL180 IN THE ALT ALERTER AND HAD TAKEN A COURSE OF DIRECT FUZZY. I WAS TOLD BY THE FO THAT ATC HAD ASSIGNED US DIRECT FUZZY, CROSS FUZZY AT FL180. IN THE MEANTIME, I WAS BUSY WITH PAPERWORK WHEN ASKED US ABOUT OUR ALT. I LOOKED AT THE ELECTRONIC ATTITUDE DIRECTOR INDICATOR AND OBSERVED THAT WE WERE ABOUT 15 NM W OF FUZZY AND STILL LEVEL AT FL270. ATC THEN ASSIGNED A 360 DEG TURN SO THAT WE COULD DSND TO CROSS FUZZY AT FL180. WE COMPLIED WITHOUT ANY FURTHER INCIDENT. DURING MY ABSENCE FROM THE FLT DECK THE VNAV HAD DISENGAGED WHILE THE FO WAS MANEUVERING THE AIRPLANE AND UPON MY RETURN I NEVER NOTICED I WAS RELYING ON THE VNAV TO INITIATE THE DSCNT, WHICH NEVER HAPPENED. THE LESSON HERE, DON'T DEPEND ON THE AUTOFLT SYS TO FLY THE AIRPLANE, BECAUSE, AS IN THIS CASE, IT MAY HAVE DISENGAGED WITHOUT YOU KNOWING.

  41.  
  42. Accession Number: 378980
    Synopsis: A B737-300 APCHING LAX, DSNDS LATE TO CROSS CIVET AT ASSIGNED ALT IN ZLA, CA, AIRSPACE.
    Narrative: FMC VNAV SYS WAS PROGRAMMED TO CROSS CIVET AT FL180. WE HAD BEEN CLRED DIRECT TO CIVET FROM SOMEWHERE IN ARIZONA. ABOUT 15 MI FROM CIVET AND PRIOR TO DSCNT WITH VNAV I NOTICED THE ACFT WAS TRACKING SEVERAL MI S OF COURSE. I SELECTED HEADING MODE ON THE MODE CTL PANEL AND TURNED THE ACFT MORE TO THE N TO INTERCEPT THE LAX RWY 25L LOC. WHEN I PUSHED THE HEADING MODE BUTTON I DIDN'T NOTICE THAT THE FMC DROPPED OUT OF VNAV MODE. WHEN I DID NOTICE, WE WERE ONLY 3 MI FROM CIVET AND STILL AT FL240. I IMMEDIATELY STARTED A MANUAL DSCNT TO FL180. ABOUT 2 MI FROM CIVET ZLA ASKED WHAT ALT WE WERE LEAVING. I RESPONDED FL240. ZLA THEN GAVE US A HDG OF 200 DEGS AND CLRED US TO 14000 FT. ADDING TO THE CONFUSION IN THE COCKPIT WAS THE FO BEING DISTRACTED BY A FLT ATTENDANT IN THE COCKPIT SHOWING HIM PICTURES IN AN ALBUM. NEXT TIME, I WILL INSURE THAT ALL EYES ARE ON THE JOB AT HAND.

  43.  
  44. Accession Number: 382720
    Synopsis: AN MD88 DSNDING INTO TPA, FL, OVERSHOOTS CLRED ALT BECAUSE OF FMC SETTINGS AND MISUNDERSTANDING OF CLRED ALT.
    Narrative: ON INITIAL DSCNT INTO TPA, APPROX 120 MI N OF FIELD, WE WERE RESTR TO .70 MACH FOR TFC. ZJX WAS STEPPING US DOWN OUT OF CRUISE ALT IN 2000 FT SEGMENTS. THE CAPT HAD TO EXIT THE FLT DECK TO GO TO THE RESTROOM. DURING THE CONFUSION, I BELIEVE THE CTLR CLRED US TO DSND TO FL310. HOWEVER, I DID NOT CHANGE THE AUTOPLT ALT WINDOW TO THE NEW ALT OF FL310. INSTEAD, IT WAS LEFT AT 33000 FT. ON THE MD88, DURING AN FMS 'CRUISE' DSCNT, IT REQUIRES SEVERAL INPUTS. THIS PROCESS IS COMPOUNDED FURTHER IF YOU ARE RESTR TO A SPD THAT IS NOT THE DEFAULT CRUISE SPD. OUR ACFT ENTERED THE 'ALT CAPTURE' MODE FOR 33000 FT. AS IT DID, THE SPD DEFAULTED TO NORMAL CRUISE SPD AND BEGAN TO ACCELERATE. I SELECTED IAS/MACH SPD ON THE AUTOPLT PANEL -- WHICH DROPPED THE 'ALT CAPTURE' BECAUSE OF AN ANOMALY IN THE SYS. THE ACFT DSNDED TO FL326 BEFORE MANUAL RECOVERY BACK TO FL330. AT FL328 THE CTLR ISSUED A CONTINUE DSCNT TO FL290. I DON'T BELIEVE THERE WAS AN ALTDEV BECAUSE WE WERE CLRED TO FL310. RECOMMEND TO CHANGE MD88 SOFTWARE SO THAT 'ALT CAPTURE' REMAINS 'ARMED' IF YOU CHANGE THE DSCNT PROFILE DURING ALT CAPTURE PHASE. SUPPLEMENTAL INFO FROM ACN 383085: WHEN I RETURNED, WE WERE DSNDING BELOW FL330 TO FL290. THE FO ASKED ME WHAT ALT WE HAD BEEN PREVIOUSLY CLRED TO AND I REPLIED THAT I BELIEVED IT WAS FL310. HE SAID THAT'S WHAT HE THOUGHT ALSO, BUT THAT WE HAD NOT CHANGED THE ALT ALERT WINDOW FROM FL330 AND HE GOT A WARNING AT FL327 AND CLBED BACK UP TO FL330 BECAUSE HE WAS UNSURE OF THE ACTUAL CLRNC. 1 OF 2 THINGS HAD HAPPENED, EITHER: 1) WE FORGOT TO CHANGE THE ALT ALERT TO FL310 WHEN WE WERE CLRED OR: 2) WE WERE ONLY CLRED TO FL330 AND ERRONEOUSLY BEGAN DSCNT BELOW FL330 BECAUSE OF A 'GLITCH' THAT EXISTS IN THE FMS SOFTWARE REGARDING THE ALT CAPTURE FEATURE.

  45.  
  46. Accession Number: 390379
    Synopsis: AN ACR DC10 FLC DSNDED BELOW THEIR ASSIGNED ALT WHEN THE AUTOPLT CHANGED MODES DURING THE ALT CAPTURE PHASE OF THE LEVELOFF.
    Narrative: ALTDEV LEVELING AT FL330. ALT WAS ARMED AT FL340. ACFT DSNDED THROUGH FL330 TO FL326. ALT WAS NOT ARMED AT FL328 WHERE WE FIRST NOTICED DEV. SUPPLEMENTAL INFO FROM ACN 390380: ALTDEV LEVELING AT FL330. DSNDING FROM FL370 DUE MODERATE TURB. ENCOUNTERED CONTINUING, THOUGH DIMINISHED, TURB APCHING LEVELOFF AT FL330. AUTOPLT WENT TO CAPTURE MODE THEN, OR SOME REASON, REVERTED TO VERT SPD MODE BEFORE REACHING FL330. CAUGHT DEV PASSING FL328. CAPT (PF) DISCONNECTED AUTOPLT AND RECOVERED EXPEDITIOUSLY TO FL330. INFORMED ATC OF CONTINUED TURB PER THEIR INQUIRY. ATC SAID NOTHING ABOUT OUR MINIMUM ALT OF FL326.

  47.  
  48. Accession Number: 390900
    Synopsis: WDB ACFT IN CRUISE AND ON LNAV. ACFT WENT OFF TRACK WHEN LNAV REVERTED TO HEADING HOLD MODE. ATC INTERVENED ALERTING FLC TO COURSE DEV.
    Narrative: ACFT HAD BEEN TRACKING THE FMS FLT PLAN RTE IN LNAV FOR THE PAST HR. CTR CALLED AND ASKED OUR NEXT FIX ON RTE OF FLT. WE REPLIED DOPHN. CTR SAID WE WERE SLIGHTLY N OF TRACK. WE THEN NOTICED LNAV HAD DISENGAGED AND WE WERE APPARENTLY IN HEADING HOLD MODE. (HEADING MODE WAS NOT ANNUNCIATED.) WE IMMEDIATELY CORRECTED BACK TO TRACK. WE APPARENTLY WERE ONLY A FEW MI OFF TRACK. LNAV WAS RE- ENGAGED AND TRACKED NORMALLY THE REST OF FLT. WE HAVE NO IDEA WHAT CAUSED THE MOMENTARY LNAV DISENGAGEMENT.

  49.  
  50. Accession Number: 397243
    Synopsis: CAPT OF AN ACR LGT FAILS TO INSURE THAT HIS FMS STARTS THE DSCNT FOR AN ALT XING RESTR.
    Narrative: WE HAD BEEN CLRED FROM FL370 TO FL290 AND THE AUTOPLT/FMS WAS ENGAGED AND MAKING THE DSCNT. UPON LEVELOFF THE FLT ATTENDANTS CAME INTO THE COCKPIT TO OFFER BEVERAGES. DURING THE LEVELOFF THE FMS MODE CHANGED FROM VNAV TO ALT HOLD. AS EVIDENCED BY LATER EVENTS, I DID NOT NOTICE THE FMS MODE CHANGE. SHORTLY AFTER LEVELING AT FL290 WE WERE CLRED TO CROSS OTT VOR AT FL250. I PROGRAMMED THE FMS AND SET THE ALT ALERT WINDOW FOR THE XING RESTR. LATER, WHEN I SHOULD'VE BEEN STARTING THE DSCNT I WAS ENJOYING THE VIEW OUT THE WINDOW AND LOST SITUATIONAL AWARENESS. I DID NOT START THE DSCNT. VNAV, WHICH I NORMALLY ONLY RELY UPON AS A BACKUP FOR DSCNTS COULD NOT START US DOWN BECAUSE THE FMS HAD PREVIOUSLY CHANGED TO ALT HOLD. AS A RESULT OF THE DISTRACTIONS AND LOSS OF SITUATIONAL AWARENESS I DID NOT START THE DSCNT UNTIL ALMOST OVER OTT VOR. THE FO ASKED IF WE WERE SUPPOSED TO CROSS AT FL250, WHEREUPON I BEGAN AN IMMEDIATE DSCNT. WE CROSSED OTT AT LEAST SEVERAL THOUSAND FT HIGH. APPARENTLY THERE WAS NO CONFLICTING TFC IN THE AREA (AT LEAST AS FAR AS WE COULD TELL FROM TCASII) AND THE CTLR SAID NOTHING ABOUT THE XING ALT. IT HAS BEEN SEVERAL YRS, AT LEAST, SINCE I'VE HAD AN ALT 'BUST.' FORTUNATELY, I WILL BE ABLE TO LEARN FROM THIS EVENT AND PAY BETTER ATTN IN THE FUTURE.

  51.  
  52. Accession Number: 401193
    Synopsis: FO OF A B737-400 ALLOWED THE ACFT TO ASCEND ABOVE ASSIGNED ALT WHEN SLOWING THE ACFT FOR DSCNT DUE MISPROGRAMMING THE FMC AUTO HOLD BEFORE IT WAS TIME FOR THEIR DSCNT.
    Narrative: ZSE WAS SLOWING US DOWN AND GIVING US VECTORS FOR SPACING INTO SEATTLE. APPROX 40 MI FROM TOP OF DSCNT, WE WERE CLRED, PLT'S DISCRETION, TO FL240, WHICH WE SET IN THE ALT ALERTER. THE FO WAS PF AND RESPONDED TO ATC AS I WAS OFF FREQ TO GET ATIS. A FLT ATTENDANT CAME UP AT THAT TIME TO TAKE AWAY OUR MEAL TRAYS AND REMIND US THAT A MEDICAL OXYGEN BOTTLE WAS NEEDED IN SEATTLE ON LNDG. WHEN I TURNED FORWARD, I NOTICED THAT WE WERE TURNING BACK TO BTG PER ATC INSTRUCTIONS, BUT THE AUTOPLT WAS IN CTL WHEEL STEERING PITCH MODE. A QUICK GLANCE AT THE ALT SHOWED THAT WE WERE CLBING AND PASSING FL316. (ASSIGNED ALT WAS FL310.) I GRABBED THE CTLS AND GENTLY PUSHED THE ELEVATOR OVER TO GET US BACK TO FL310. OUR ALTIMETER SHOWED WE GOT TO FL318 BEFORE WE STARTED BACK DOWN. NO ALT ALERTER WENT OFF BECAUSE WE HAD FL240 IN THE MCP. I AM NOT SURE HOW THE ACFT GOT INTO CTL WHEEL STEERING PITCH MODE, BUT THE LACK OF ANY BELLS, MY ATTN DIVERTED TO THE FLT ATTENDANT, BUSY ATC INSTRUCTIONS, AND THE FO NOT NOTICING WHAT MODE THE AIRPLANE HAD DOWNGRADED TO, CAUSED US TO BUST OUR ALT.

  53.  
  54. Accession Number: 401425
    Synopsis: LGT ACFT ON STAR ARR AND DSNDING TO CAPTURE GS. RPTR FO, PNF, WAS INSTRUCTED BY CAPT TO RESET ALT ABOVE ACFT SO HE COULD CONTINUE IN 'OPEN DSCNT' TO CAPTURE GS, BUT THE FMA REVERTED TO VERT SPD. CAPT WANTED OPEN DSCNT SO WHEN RPTR SET IT THE ACFT REVERTED TO OPEN CLB, PWR INCREASING FOR CLB AND SPD INCREASED, OVERSPEEDING THE FLAP SETTING.
    Narrative: CAPT WAS HAND FLYING, AUTOTHRUST 'ON.' WHILE STEPPING DOWN ON THE CIVIT 4 ARR AT LAX AND TRANSITIONING TO THE ILS FROM ABOVE THE GS WE EXPERIENCED A FLAP OVERSPD. WITH 5000 FT SET IN THE ALT WINDOW AND IN 'OPEN DSCNT,' SLOWING AS ASSIGNED BY ATC AND DSNDING TO CAPTURE THE GS, THE PF TOLD ME TO SET THE ALT ABOVE OUR PRESENT ALT (SO THE ACFT WOULD CONTINUE DSNDING PAST 5000 FT TO CAPTURE THE GS). I DID THIS AND THE FMA REVERTED TO VERT SPD. I TOLD THE CAPT I'D GIVE HIM 1000 FT VERT SPD DOWN TO CAPTURE THE GS, THIS WAY THE FLT DIRECTOR WOULD MATCH WHAT WE WERE DOING. HE SAID HE DIDN'T LIKE THAT MODE, AND TO GIVE HIM OPEN DSCNT INSTEAD, SO I PULLED THE ALT KNOB TO DO SO, FORGETTING THAT I HAD SPUN THE ALT KNOB UP TO SOMETHING ABOVE OUR PRESENT ALT, AND NOT CHKING THE FMA AFTER DOING SO. IF I HAD CHKED THE FMA, I WOULD HAVE SEEN 'OPEN CLB.' THIS CAUSED THE ENGS TO SPOOL UP TOWARDS CLB PWR, RAPIDLY ACCELERATING US TO VFE +10 KTS. CONTRIBUTING TO THIS WAS OUR ENTRY INTO A CLOUD BUILDUP, FURTHER INCREASING OUR AIRSPD. ALSO, THE THROTTLES ON THIS ACFT DON'T MOVE IN THE AUTOTHROTTLE MODE (ONE LESS CLUE AS TO ENG THRUST TRENDS). THIS COULD BE PREVENTED BY 1) CONTINUING TO STEP THE ALT DOWN UNTIL GS CAPTURE, 2) NEVER TOUCHING THE FLT CTL UNIT UNTIL TOLD TO DO SO BY THE PF, 3) ALWAYS CHKING THE FMA'S (FLT MODE ANNUNCIATOR) AFTER AN FCU INPUT.

  55.  
  56. Accession Number: 402690
    Synopsis: A DSNDING MD90 DSNDS BELOW THE ALT XING AS DESIGNATED FOR KAYOH INTXN WHEN THE FMS MALFUNCTIONS AND DISTRACTS THE CREW FROM THEIR DSCNT PROC.
    Narrative: WE WERE CLRED TO CROSS KAYOH AT 7000 FT AND PROCEED VIA EASTSIDE 3 ARR. THE CAPT WAS USING A VNAV DSCNT SETUP FOR THE EASTSIDE 3 FMS STAR AND VERIFIED BY BOTH PLTS. DURING OUR DSCNT TO 7000 FT THE CAPT NOTICED A MAP FAILURE AND ATTEMPTED TO UPDATE THE ACFT POS. I NOTICED OUR NAV DISPLAYS SHOWED THE RTE AS A DASHING BLUE LINE INSTEAD OF THE NORMAL PINK RTE LINE. THE AUTOPLT REMAINED ON IN THE 'HEADING HOLD' MODE AND VERT SPD. SINCE THE FMS WAS SET UP FOR THE STAR THE CAPT HAD RESET THE DIGITAL FLT GUIDANCE COMPUTER ALT TO 3300 FT FOR 'SNAKE INTXN.' I ATTEMPTED TO REGAIN OUR ARR SINCE WE WERE ON AN 'FMS STAR' WITH NO NAVAID BACKUPS. AFTER REACTIVATING THE RTE AND EXECUTING, THE NAV DISPLAY SHOWED A NORMAL DISPLAY. THE CAPT RE-ENGAGED NAV AND ATTEMPTED TO RE-ENGAGE VNAV. THE FMS DISPLAYED 'NO VERT NAV' AND 'NO PERFORMANCE DATA.' AS I WAS ENTERING THE PERFORMANCE DATA THE AUTOPLT AGAIN SWITCHED TO 'HEADING HOLD AND VERT SPD' MODE. AT THIS TIME ATC RADIOED ABOUT OUR ALT APPROX 5900 FT MSL. THE CAPT IMMEDIATELY DISCONNECTED THE AUTOPLT AND STARTED A CLB TO 7000 FT MSL. ATC ASKED IF WE WERE VMC, WHICH WE WERE, AND CLRED US TO PROCEED VISUALLY, MAINTAINING TERRAIN CLRNC AT 5000 FT OR ABOVE. THE REST OF THE FLT WAS UNEVENTFUL. TO PREVENT RECURRENCE I'LL NOTIFY ATC IMMEDIATELY WITH EQUIP FAILURES. ENSURE SOMEONE IS FLYING THE AIRPLANE WHILE THE OTHER PLT CORRECTS THE MALFUNCTION. PROVIDE A BETTER BACK UP FOR THE PF. SUPPLEMENTAL INFO FROM ACN 402691: I THEN NOTICED THE AUTOPLT HAD AGAIN GONE TO 'HEADING HOLD' AND WAS STILL IN 'VERT SPD' DSCNT AND I WAS 1200 FT OR 1300 FT BELOW 7000 FT AND 2 OR 3 MI E OF KAYOH. I KICKED OFF THE AUTOPLT AND STARTED A CLB BACK UP TO 7000 FT WHEN SOCAL CALLED AND SAID WE WERE CLRED TO DSND AND THEN SAID WE WERE TOO LOW AND TO CLB BACK TO...THEN HE ASKED IF WE WERE VFR. TO PREVENT A RECURRENCE, I'LL SET THE ALT WINDOW FOR THE BOTTOM ALT AT EACH WAYPOINT ON THE STAR.

  57.  
  58. Accession Number: 407580
    Synopsis: ARTCC CTLR ASSIGNS NEW CLRNC WHEN OBSERVING A B757 FLC CROSS ASSIGNED COURSE. FLC WAS IN LNAV EQUIP MODE. FLC DID NOT OBSERVE DEV FROM ASSIGNED RTE.
    Narrative: I WAS THE PLT FLYING THE ACFT. THE ACFT WAS ON AUTOPLT WITH THE LNAV ENGAGED WHEN WE WERE CLRED TO BRIGS INTXN. I WATCHED THE ACFT MAKE THE TURN TO MAYZE INTXN TO JOIN J6O. AFTER PASSING ASHEN INTXN, ZOB CALLED TO ASK IF WE WERE ON A HEADING. NEITHER THE CAPT OR I COULD REMEMBER IF WE HAD BEEN GIVEN A HEADING, BUT THE ACFT WAS IN HDG MODE AND 6.5 MI R OF COURSE. WE SHOULD HAVE MADE A 20 DEG L TURN TO JOIN THE AIRWAY AT MAYZE INTXN. I SHOULD HAVE BEEN MONITORING THE ACFT CLOSELY, BUT RELAXED ONCE WE HAD REACHED CRUISE ALT AND ESTABLISHED ON COURSE. I STILL DO NOT KNOW HOW WE ENDED UP IN HEADING MODE. SUPPLEMENTAL INFO FROM ACN 406785: UNKNOWN HOW AUTOPLT GOT OFF OF LNAV TRACKING. CORRECTED BACK ON COURSE.

  59.  
  60. Accession Number: 407880
    Synopsis: A CL65RJ ON APCH TO CVG FLIES THROUGH THE LOC COURSE WHEN THE AUTO-CAPTURE MODE OF THE AUTOPLT DEFAULTS TO THE HEADING MODE.
    Narrative: AFTER BEING CLR FOR ILS RWY 18R AT CVG AND ARMING THE APCH MODE ON AUTOPLT, APPARENTLY THE MODE CTL DEACTIVATED AND DEFAULTED TO HEADING MODE. DID NOT NOTICE UNTIL FLYING THROUGH THE LOC. AUTOPLT WAS DISCONNECTED AND WE TURNED BACK TO THE RWY 18R LOC. NO CONFLICT WITH TFC WAS NOTED.

  61.  
  62. Accession Number: 408150
    Synopsis: FLC OF A B737-300 CLBED ABOVE ASSIGNED ALT DUE TO THE AUTOPLT ALT HOLD MODE DISCONNECTING DUE TO HIGHER THAN CRUISE PWR SETTING.
    Narrative: WE WERE AT FL280 WITH DISCRETION TO FL240 AND AT AN ASSIGNED SPD OF 280 KTS. ZHU CHANGED OUR SPD TO 300 KTS. I INCREASED OUR AIRSPD TO 300 KTS BY MEANS OF THE MODE CTL PANEL. DURING ALL OF THE SPD CHANGES, THE CAPT AND MYSELF WERE HAVING A DISCUSSION ON CONVERTING CENTIGRADE TEMP TO FAHRENHEIT TEMP. AFTER A WHILE THE CTLR ASKED ABOUT OUR ALT. THE ACFT HAD BEGUN A SLOW CLB FROM FL280 TO FL290. THE CAPT AND MYSELF HAD A LONG DISCUSSION ON THIS INCIDENT. WE THINK THAT WHEN I INCREASED THE AIRSPD THE ENGS ACCELERATED THE ACFT TO THE POINT THAT THE AUTOPLT COULD NOT KEEP UP WITH THE ACCELERATION. THE PITCH MODE OF THE AUTOPLT DISCONNECTED AND IT BEGAN A SLOW CLB. SINCE WE WERE IN A CRUISE PORTION OF FLT WE MISSED THE ACFT WAS IN A CLB. IN ADDITION TO CLB AND DSCNT LEVELOFFS, I WILL WATCH SPD CHANGES TO MAKE SURE WE DON'T GO THROUGH ON ALT.

  63.  
  64. Accession Number: 408440
    Synopsis: B737 CREW HAD FLT GUIDANCE CHANGE FROM ALT HOLD TO CTL WHEEL STEERING PITCH. THIS RESULTED IN A 1000 FT ALT EXCURSION.
    Narrative: WE WERE AT FL280. ATC HAD GIVEN US 'PLT'S DISCRETION TO FL240.' IT WAS THE FO'S LEG TO FLY. ATC DIRECTED US TO MAINTAIN 300 KIAS. AT THAT MOMENT WE WERE CRUISING AT 280 KIAS. I VISUALLY CONFIRMED THAT THE FO HAD DIALED 300 KIAS INTO THE MCP AIRSPD WINDOW. APPROX 1 MIN LATER, ATC SAID TO US, 'CALL SIGN, SAY YOUR ALT.' SINCE WE HAD BEEN GIVEN A FREQ CHANGE BTWN THE TIME WE WERE GIVEN PLT'S DISCRETION TO FL240 AND NOW, I THOUGHT MAYBE THERE HAD BEEN A FAILURE TO COM BTWN THE LAST SECTOR CTLR AND THIS ONE. I GLANCED AT THE FMC TO CONFIRM WE WERE NOT YET AT OUR TOP OF DSCNT POINT AND REPLIED, 'CALL SIGN WAS GIVEN PLT'S DISCRETION TO FL240.' THEN ATC REPLIED, 'CALL SIGN, SAY YOUR ALT.' WELL, I WAS SURE WE WERE STILL AT FL280 (BECAUSE THAT HAD BEEN OUR CRUISING ALT, AND WE HAD NOT YET STARTED OUR DSCNT), BUT A QUICK GLANCE AT MY INSTS TOLD ME I WAS DEAD WRONG, AND WE HAD A PROB. WITH NO WARNING WHATSOEVER, AND FOR NO APPARENT REASON, THE ACFT HAD BEGUN A VERY SLOW CLB, AND WAS NOW NEARING FL290. AT THE SAME INSTANT I SAW OUR ALTDEV, I ALSO SAW THAT THE PITCH MODE OF THE AUTOPLT HAD REVERTED FROM 'ALT HOLD' TO 'CTL WHEEL STEERING PITCH.' FOR THOSE NOT COMPLETELY FAMILIAR WITH THE B737-500 AUTOPLT, CTL WHEEL STEERING PITCH IS AN AUTOPLT MODE DESIGNED TO MAINTAIN A CONSTANT PITCH ATTITUDE. THE ACFT WAS AT THE MOMENT OF REVERSION TO CTL WHEEL STEERING PITCH. WELL, THAT PART OF THE SYS WORKED AS ADVERTISED. BUT REMEMBER, WE HAD ACCELERATED FROM 280 KIAS TO 300 KIAS. AND (LESSON FROM BASIC AIRMANSHIP 101) A CONSTANT PITCH AT AN INCREASING AIRSPD RESULTS IN -- THAT'S RIGHT -- A CLB. I IMMEDIATELY TOOK CTL OF THE ACFT AND BEGAN A DSCNT, NOT JUST BACK DOWN TO FL280, BUT CONTINUING DOWN TO FL240. SIMULTANEOUSLY I KEYED THE MIKE AND TOLD CTR, 'CALL SIGN IS AT FL290, DSNDING NOW TO FL240. OUR AUTOPLT APPEARS TO HAVE MALFUNCTIONED.' CTR REPLIED, 'ROGER, COPY YOU DSNDING TO FL240.' WE HAD NO TCASII ALERT OF ANY KIND, AND WHEN I ASKED THE CTLR IF I NEEDED TO CALL HIM WHEN WE GOT ON THE GND, HE REPLIED 'NO, DON'T WORRY ABOUT IT.' IN MY 12 1/2 YRS AND 11000 HRS ON B737-300/500 ACFT, I HAVE NEVER SEEN THIS HAPPEN. I HAVE SEEN THE AUTOPLT ON THE B737-300/500 REVERT TO CTL WHEEL STEERING PITCH FOR ONLY 3 REASONS: 1) MANUALLY DESELECTING ALL OTHER PITCH MODES. (THIS DID NOT HAPPEN.) 2) TURB SO BAD THE AUTOPLT CANNOT MAINTAIN ALT. (WE WERE IN PERFECTLY SMOOTH RIDE CONDITIONS.) 3) A FORCE BEING APPLIED TO THE FLT CTLS SIGNIFICANT ENOUGH TO CAUSE THE SELECTED AUTOPLT PITCH MODE TO DISENGAGE. THIS IS THE ONLY POSSIBILITY I CAN THINK OF. WHAT MAY HAVE HAPPENED IS THAT THE NOSE-UP PITCH FORCES RESULTING FROM THE PWR ADVANCING TO ACCELERATE FROM 280 KIAS TO 300 KIAS WERE SIGNIFICANT ENOUGH TO CAUSE THE AUTOPLT TO REVERT FROM 'ALT HOLD' TO 'CTL WHEEL STEERING PITCH.' NORMALLY WE WOULD GET A WARNING HORN IF THE ACFT DEVIATED FROM THE SELECTED CRUISE ALT BY MORE THAN 150 FT. BUT IN THIS CASE, BECAUSE WE HAD DIALED FL240 INTO THE ALT WINDOW ON THE MCP TO COMPLY WITH OUR CLRNC, WHEN THE ACFT DEPARTED FL280, EVEN THOUGH IT WAS CLBING INSTEAD OF DSNDING, WE GOT NO WARNING HORN AND NO ALT ALERT LIGHT. ALSO, BECAUSE THE AUTOPLT HAD NOT COMPLETELY DISENGAGED, WE GOT NO 'AUTOPLT DISENGAGED' WARNING TONE OR LIGHT. WHAT APPARENTLY HAPPENED WAS THE CTL WHEEL STEERING PITCH APPEARED ON THE EFIS DISPLAY. I HAD MY HEAD DOWN AT THE MOMENT THIS OCCURRED AND WAS NOT LOOKING AT THE INST PANEL. THE FO, WITH NO REASON TO EXPECT ANY ANOMALY, DID NOT NOTICE THE CTL WHEEL STEERING PITCH DISPLAY APPEAR. AND THE CLB WAS SO SLOW THAT NEITHER THE FO NOR I HAD ANY 'SEAT-OF-THE-PANTS' INDICATION WE HAD DEPARTED ALT. RECOMMENDATIONS: HUMAN FACTORS: 1) INCREASED VIGILANCE. 2) GET THE WORD OUT HOW THIS CAN HAPPEN. MECHANICAL: CONDUCT INSPECTIONS TO DETERMINE IF THE 'PENDULUM EFFECT' RESULTING FROM LARGE PWR CHANGES IN B737'S IS SIGNIFICANT ENOUGH TO CAUSE AUTOPLT REVERSION TO CTL WHEEL STEERING PITCH IN A STATISTICALLY SIGNIFICANT NUMBER OF ACFT.

  65.  
  66. Accession Number: 409112
    Synopsis: A B737-300 FLC CRUISING THROUGH ZMP AIRSPACE TESTS THE FUEL GAUGES AND TAKES THE AUTOFLT SYS OUT OF VNAV. THE ACFT HAS AN ALT EXCURSION OF 400 FT.
    Narrative: B737-300 IN CRUISE AT FL350, AUTOPLT ENGAGED IN VNAV. I TESTED THE FUEL GAUGES, AND FOR SOME REASON THE VNAV DISCONNECTED AND THE AUTOPLT DID NOT DEFAULT TO ALT HOLD, BUT RATHER STARTED A SLOW DSCNT. WE DID NOT PICK UP THE DSCNT UNTIL THE ALT ALERT HORN SOUNDED AT 300 FT BELOW FL350. I TOOK CORRECTIVE ACTION BY DISENGAGING THE AUTOPLT AND RETURNING TO FL350. THE ACFT DSNDED TO ABOUT 400 FT BELOW OUR ASSIGNED ALT OF FL350. TESTING THE FUEL GAUGES RESULTED IN VNAV DISENGAGEMENT. HOWEVER ON EACH SUBSEQUENT TEST THE AUTOPLT DEFAULTED TO ALT HOLD AND DID NOT CHANGE ALT.

  67.  
  68. Accession Number: 409279
    Synopsis: B767 CRUISING AT FL350. CAPT FAILED TO INITIATE DSCNT WHEN CLRED TO LOWER ALT DUE TO UNMONITORED VNAV MALFUNCTION.
    Narrative: 30 NM W OF MOL, WHILE AT FL350, ZDC CLRED US TO DSND TO FL330. WE RESET THE ALT WINDOW TO FL330 AND SELECTED FL330 AS CRUISE ALT IN CDU. WE HAD BEEN OPERATING IN VNAV BUT FOR SOME UNKNOWN REASON THE ACFT THEN REVERTED TO ALT HOLD. I, AS THE PF, FAILED TO CHK THE ADI FOR THE APPROPRIATE DSCNT INDICATIONS AND WENT ABOUT REVIEWING THE ARR PROCS FOR JFK. A MIN OR 2 LATER, CTR CALLED AND ASKED IF WE HAD RECEIVED THE DSCNT TO FL330. I THEN INITIATED THE DSCNT USING FLT LEVEL CHANGE. THE FLT CONTINUED WITHOUT FURTHER INCIDENT. LESSON LEARNED: CHK WHAT IS ACTUALLY ON YOUR PLATE. SUPPLEMENTAL INFO FROM ACN 409280: WE RESET THE ALT WINDOW BUT FAILED TO NOTICE THAT WE HAD NOT ENGAGED THE AUTOPLT TO START THE DSCNT.

  69.  
  70. Accession Number: 414120
    Synopsis: AN MD88 FLC DOES NOT START DOWN AFTER RECEIVING THEIR DSCNT CLRNC. THE CREW WAS INTERRUPTED BY THE FLT ATTENDANT AND THE CTR CTLR HAD TO ASK THE CREW ABOUT THEIR ALT.
    Narrative: AT FL310, TOP OF DSCNT, COPLT'S LEG, FLT RDU-CVG CLRED DIRECT DRESR TO CROSS IT AT FL240. I CALLED OUT OF FL310, SAW COPLT SET UP FMS AND AUTOPLT FOR DSCNT. AT SAME TIME, FLT ATTENDANT CALLED TO OFFER BREAKFAST. AS HE BROUGHT FOOD FORWARD, ZID ASKED OUR ALT AND IF WE WOULD MAKE THE RESTR AT DRESR. I LOOKED UP AT THE ALTIMETERS. WE WERE STILL AT FL310. I PUT ACFT INTO RAPID DSCNT (IAS MODE, .80 MACH, IDLE, SPD BRAKES). WHEN WE WERE 2 MI FROM DRESR AT FL260, DSNDING AT OVER 6000 FPM, CTLR GAVE US A 90 DEG TURN TO R. WE TURNED LESS THAN 30 DEGS BEFORE HE CLRED DIRECT TO OUR NEXT NAV POINT. I CHKED TCASII. THERE WAS NOT ANOTHER ACFT FOR 20 MI. I DO NOT BELIEVE THERE WAS A LOSS OF SEPARATION. IF THERE IS A LESSON LEARNED FOR ME, THIS ACFT'S AUTOMATION HAS CERTAIN PITFALLS THAT I MUST BE SPECIALLY AWARE OF. ALSO, WHEN I AM THE PNF, I NEED TO CHK WHAT THE PF IS DOING, RELIGIOUSLY, AND LEARN TO FILTER OUT DISTRS. SUPPLEMENTAL INFO FROM ACN 414123: BEGAN DSCNT VIA VNAV PATH, CAPT CALLED OUT OF FL310. ACFT INTERCEPTED AND BEGAN DSCNT. AT THIS TIME FLT ATTENDANT KNOCKED ON DOOR TO OFFER BREAKFAST. SHORTLY AFTER THIS, CTR ASKED OUR ALT. WE CHKED AND ACFT WAS BACK AT FL310 IN VNAV LEVEL. THE ACFT HAD DSNDED 300 FT INITIALLY, BUT AT SOME TIME DURING THIS PERIOD MUST HAVE RETURNED TO VNAV LEVEL UNNOTICED BY MYSELF OR THE CAPT. WE LEVELED AT FL240 OVER DRESR AND PROCEEDED WITH CONTINUATION OF ARR/APCH. XING ALT WOULD HAVE BEEN MADE, BUT WE HAD RPTED OUT OF FL310 EARLIER AND WERE STILL LEVEL AND WERE UNSURE AT TIME IF WE WOULD MAKE ALT RESTR.
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