Narrative:

During climb out; the autothrottle system disengaged twice and we received an upper EICAS message. We cycled the master autothrottle switch; and the system reconnected both times. Further in the flight; while at cruise at FL340 over the ocean; and talking to commercial radio on HF; we received simultaneously multiple EICAS messages; flight instruments failure flags on captain's side; and I got out the flight manual to troubleshoot the multiple issues. Since it was virtually impossible to talk; communicate; or even think with the warning horn sounding that could not be silenced; I proceeded to attempt to locate the circuit breakers that would silence the multiple warning horns sounding in the cockpit. We had orange failure flags on all of the captain's air data instruments; a red flaps EICAS message; a red confign EICAS message; 3 green gear down lights (gear was not down); and status messages for nose air/ground disagreement; main air/ground disagreement; GPWS fail; landing gear monitor; and warning 'elex.' the flaps/confign and warning horn stopped and messages cleared before I could find the problem or the circuit breaker; so I went to solve the captain's air data issue. We were able to recover the captain's air data instruments using the xfer switch utilizing the first officer air data computer to now drive all the air/data instruments; except standby. Shortly after that; the warning horn sounded again; and we again got all of the previous EICAS messages. I was able to locate the 2 circuit breakers and was ready to pull them when the warning ceased again. The flight attendants called the cockpit about that time as they clearly heard the audio warnings and were wondering if everything was ok. About that time; we needed to check-in with center on VHF. I directed the first officer to check in with center; and advise them that we were unable rvsm (due to the loss of the captain's air data computer) for remainder of flight. It did not seem to be an issue with them. We still had the multiple status messages on the lower EICAS screen. We were fortunate enough to have 2 mechanics on board; and I asked one of them to come to the flight deck to utilize their knowledge. I also initiated a phone patch with dispatch and maintenance at that time to discuss the condition of the aircraft and our options. Maintenance was unable to resolve our issues with the aircraft over the radio. Dispatch provided some diversion airport WX. Also; about this time; I got a message from the dispatcher asking me what my concern was regarding the aircraft; and that he had been directed to ask! This request was most unusual; and I provided the answer of multiple failures of unrelated system and loss of the captain's air/data instruments. I also asked the dispatcher who wanted to know. It turned out to be one of the scheduling controllers. I did not feel his questions were needed at that time and discounted them; nor did he need to be in the loop concerning my judgement of the condition of our aircraft. We decided to continue to ZZZ as the aircraft was under control; the WX was good; the captain's flight instruments were restored; and we only now had status messages and no upper EICAS messages. The first officer and myself were very concerned as to the connection between the ground sensing system and the loss of the captain's air data computer; as these system seem to be completely unrelated; and they all failed at the same time. The mechanic also could not understand this. We decided to ask the flight attendants to do a cabin advisory; and I made a request to center for emergency equipment to be standing by upon our arrival. I also advised dispatch of our request for emergency equipment for precautionary reasons; and he concurred and said that he would pass the request and message on to ZZZ. I made a PA to the passenger telling them of our situation as well. Later in the flight; I again asked another center controller for emergency equipment upon arrival; and he said that he would forward the request to approach. Since there was no flight manual procedure to deal with the issue we had; I decided that we would slow early in the arrival phase; drop the gear to ascertain the proper operation of the gear position and air/ground sensing circuits to be sure that speed brakes; reversers; and antiskid would be operational upon touchdown. I also decided that since we already had 2 occurrences of the aircraft actually going into the ground mode (the warning horn we surmised was the takeoff warning horn with flaps up and cruise power set); I decided and the mechanic and first officer concurred that we would not arm the automatic speed brakes; as I did not want them deploying at a low altitude during the approach in case the throttles were near idle and the aircraft again went into the ground mode. We got delay vectors and eventually holding from approach while we worked out our issues; and I again asked for the emergency equipment. I was asked if we were declaring an emergency and required expedited handling into ZZZ. I told the controller no; but that in fact we would need a delay for landing while we worked out our issues; but that we wanted the equipment standing by as a precaution. The approach controller asked me for souls on board and fuel remaining; which I provided. When we were satisfied with the condition of the aircraft; we headed for ZZZ for a normal landing on runway xxl. However; there was no emergency equipment standing by waiting for us upon landing anywhere. I thought this strange; but decided not to query the controllers on the air asking for an explanation. We taxied to the gate with no further issues. We entered all of the maintenance items into ACARS and left the aircraft for the hotel. The aircraft was still OTS 2 days later still undergoing repair. I talked to the flight duty manager that evening about our flight. In particular; I was concerned that the company had canceled our request for emergency equipment that I requested. He said he doubted it but would investigate it the next day and get back to me. He called me the next day; and it seems there was a miscom between the approach controller and ZZZ tower on their telephone; and this is how the request was canceled. This would not have been a good situation had something gone wrong upon landing. Callback conversation with reporter revealed the following information: the reporter stated that the air data computer was replaced. The aircraft was out of service for at least two days investigating the air/ground sensing anomaly. During the event; in addition to the numerous warnings; the aircraft was slowly depressurizing as though it were on the ground after landing. The failure of emergency equipment to respond is still being investigated.

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Original NASA ASRS Text

Title: OVERWATER B757-200 DISPLAYED MULTIPLE EICAS MESSAGES; FLIGHT INST FAILURE FLAGS AND A WARNING HORN THAT WOULD NOT SILENCE. THE WARNINGS CEASED; AND THE FLT CREW CONTINUED TO DEST.

Narrative: DURING CLBOUT; THE AUTOTHROTTLE SYS DISENGAGED TWICE AND WE RECEIVED AN UPPER EICAS MESSAGE. WE CYCLED THE MASTER AUTOTHROTTLE SWITCH; AND THE SYS RECONNECTED BOTH TIMES. FURTHER IN THE FLT; WHILE AT CRUISE AT FL340 OVER THE OCEAN; AND TALKING TO COMMERCIAL RADIO ON HF; WE RECEIVED SIMULTANEOUSLY MULTIPLE EICAS MESSAGES; FLT INSTS FAILURE FLAGS ON CAPT'S SIDE; AND I GOT OUT THE FLT MANUAL TO TROUBLESHOOT THE MULTIPLE ISSUES. SINCE IT WAS VIRTUALLY IMPOSSIBLE TO TALK; COMMUNICATE; OR EVEN THINK WITH THE WARNING HORN SOUNDING THAT COULD NOT BE SILENCED; I PROCEEDED TO ATTEMPT TO LOCATE THE CIRCUIT BREAKERS THAT WOULD SILENCE THE MULTIPLE WARNING HORNS SOUNDING IN THE COCKPIT. WE HAD ORANGE FAILURE FLAGS ON ALL OF THE CAPT'S AIR DATA INSTS; A RED FLAPS EICAS MESSAGE; A RED CONFIGN EICAS MESSAGE; 3 GREEN GEAR DOWN LIGHTS (GEAR WAS NOT DOWN); AND STATUS MESSAGES FOR NOSE AIR/GND DISAGREEMENT; MAIN AIR/GND DISAGREEMENT; GPWS FAIL; LNDG GEAR MONITOR; AND WARNING 'ELEX.' THE FLAPS/CONFIGN AND WARNING HORN STOPPED AND MESSAGES CLRED BEFORE I COULD FIND THE PROB OR THE CIRCUIT BREAKER; SO I WENT TO SOLVE THE CAPT'S AIR DATA ISSUE. WE WERE ABLE TO RECOVER THE CAPT'S AIR DATA INSTS USING THE XFER SWITCH UTILIZING THE FO AIR DATA COMPUTER TO NOW DRIVE ALL THE AIR/DATA INSTS; EXCEPT STANDBY. SHORTLY AFTER THAT; THE WARNING HORN SOUNDED AGAIN; AND WE AGAIN GOT ALL OF THE PREVIOUS EICAS MESSAGES. I WAS ABLE TO LOCATE THE 2 CIRCUIT BREAKERS AND WAS READY TO PULL THEM WHEN THE WARNING CEASED AGAIN. THE FLT ATTENDANTS CALLED THE COCKPIT ABOUT THAT TIME AS THEY CLEARLY HEARD THE AUDIO WARNINGS AND WERE WONDERING IF EVERYTHING WAS OK. ABOUT THAT TIME; WE NEEDED TO CHK-IN WITH CTR ON VHF. I DIRECTED THE FO TO CHK IN WITH CTR; AND ADVISE THEM THAT WE WERE UNABLE RVSM (DUE TO THE LOSS OF THE CAPT'S ADC) FOR REMAINDER OF FLT. IT DID NOT SEEM TO BE AN ISSUE WITH THEM. WE STILL HAD THE MULTIPLE STATUS MESSAGES ON THE LOWER EICAS SCREEN. WE WERE FORTUNATE ENOUGH TO HAVE 2 MECHS ON BOARD; AND I ASKED ONE OF THEM TO COME TO THE FLT DECK TO UTILIZE THEIR KNOWLEDGE. I ALSO INITIATED A PHONE PATCH WITH DISPATCH AND MAINT AT THAT TIME TO DISCUSS THE CONDITION OF THE ACFT AND OUR OPTIONS. MAINT WAS UNABLE TO RESOLVE OUR ISSUES WITH THE ACFT OVER THE RADIO. DISPATCH PROVIDED SOME DIVERSION ARPT WX. ALSO; ABOUT THIS TIME; I GOT A MESSAGE FROM THE DISPATCHER ASKING ME WHAT MY CONCERN WAS REGARDING THE ACFT; AND THAT HE HAD BEEN DIRECTED TO ASK! THIS REQUEST WAS MOST UNUSUAL; AND I PROVIDED THE ANSWER OF MULTIPLE FAILURES OF UNRELATED SYS AND LOSS OF THE CAPT'S AIR/DATA INSTS. I ALSO ASKED THE DISPATCHER WHO WANTED TO KNOW. IT TURNED OUT TO BE ONE OF THE SCHEDULING CTLRS. I DID NOT FEEL HIS QUESTIONS WERE NEEDED AT THAT TIME AND DISCOUNTED THEM; NOR DID HE NEED TO BE IN THE LOOP CONCERNING MY JUDGEMENT OF THE CONDITION OF OUR ACFT. WE DECIDED TO CONTINUE TO ZZZ AS THE ACFT WAS UNDER CTL; THE WX WAS GOOD; THE CAPT'S FLT INSTS WERE RESTORED; AND WE ONLY NOW HAD STATUS MESSAGES AND NO UPPER EICAS MESSAGES. THE FO AND MYSELF WERE VERY CONCERNED AS TO THE CONNECTION BTWN THE GND SENSING SYS AND THE LOSS OF THE CAPT'S ADC; AS THESE SYS SEEM TO BE COMPLETELY UNRELATED; AND THEY ALL FAILED AT THE SAME TIME. THE MECH ALSO COULD NOT UNDERSTAND THIS. WE DECIDED TO ASK THE FLT ATTENDANTS TO DO A CABIN ADVISORY; AND I MADE A REQUEST TO CTR FOR EMER EQUIP TO BE STANDING BY UPON OUR ARR. I ALSO ADVISED DISPATCH OF OUR REQUEST FOR EMER EQUIP FOR PRECAUTIONARY REASONS; AND HE CONCURRED AND SAID THAT HE WOULD PASS THE REQUEST AND MESSAGE ON TO ZZZ. I MADE A PA TO THE PAX TELLING THEM OF OUR SITUATION AS WELL. LATER IN THE FLT; I AGAIN ASKED ANOTHER CTR CTLR FOR EMER EQUIP UPON ARR; AND HE SAID THAT HE WOULD FORWARD THE REQUEST TO APCH. SINCE THERE WAS NO FLT MANUAL PROC TO DEAL WITH THE ISSUE WE HAD; I DECIDED THAT WE WOULD SLOW EARLY IN THE ARR PHASE; DROP THE GEAR TO ASCERTAIN THE PROPER OP OF THE GEAR POS AND AIR/GND SENSING CIRCUITS TO BE SURE THAT SPD BRAKES; REVERSERS; AND ANTISKID WOULD BE OPERATIONAL UPON TOUCHDOWN. I ALSO DECIDED THAT SINCE WE ALREADY HAD 2 OCCURRENCES OF THE ACFT ACTUALLY GOING INTO THE GND MODE (THE WARNING HORN WE SURMISED WAS THE TKOF WARNING HORN WITH FLAPS UP AND CRUISE PWR SET); I DECIDED AND THE MECH AND FO CONCURRED THAT WE WOULD NOT ARM THE AUTO SPD BRAKES; AS I DID NOT WANT THEM DEPLOYING AT A LOW ALT DURING THE APCH IN CASE THE THROTTLES WERE NEAR IDLE AND THE ACFT AGAIN WENT INTO THE GND MODE. WE GOT DELAY VECTORS AND EVENTUALLY HOLDING FROM APCH WHILE WE WORKED OUT OUR ISSUES; AND I AGAIN ASKED FOR THE EMER EQUIP. I WAS ASKED IF WE WERE DECLARING AN EMER AND REQUIRED EXPEDITED HANDLING INTO ZZZ. I TOLD THE CTLR NO; BUT THAT IN FACT WE WOULD NEED A DELAY FOR LNDG WHILE WE WORKED OUT OUR ISSUES; BUT THAT WE WANTED THE EQUIP STANDING BY AS A PRECAUTION. THE APCH CTLR ASKED ME FOR SOULS ON BOARD AND FUEL REMAINING; WHICH I PROVIDED. WHEN WE WERE SATISFIED WITH THE CONDITION OF THE ACFT; WE HEADED FOR ZZZ FOR A NORMAL LNDG ON RWY XXL. HOWEVER; THERE WAS NO EMER EQUIP STANDING BY WAITING FOR US UPON LNDG ANYWHERE. I THOUGHT THIS STRANGE; BUT DECIDED NOT TO QUERY THE CTLRS ON THE AIR ASKING FOR AN EXPLANATION. WE TAXIED TO THE GATE WITH NO FURTHER ISSUES. WE ENTERED ALL OF THE MAINT ITEMS INTO ACARS AND LEFT THE ACFT FOR THE HOTEL. THE ACFT WAS STILL OTS 2 DAYS LATER STILL UNDERGOING REPAIR. I TALKED TO THE FLT DUTY MGR THAT EVENING ABOUT OUR FLT. IN PARTICULAR; I WAS CONCERNED THAT THE COMPANY HAD CANCELED OUR REQUEST FOR EMER EQUIP THAT I REQUESTED. HE SAID HE DOUBTED IT BUT WOULD INVESTIGATE IT THE NEXT DAY AND GET BACK TO ME. HE CALLED ME THE NEXT DAY; AND IT SEEMS THERE WAS A MISCOM BTWN THE APCH CTLR AND ZZZ TWR ON THEIR TELEPHONE; AND THIS IS HOW THE REQUEST WAS CANCELED. THIS WOULD NOT HAVE BEEN A GOOD SITUATION HAD SOMETHING GONE WRONG UPON LNDG. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT THE AIR DATA COMPUTER WAS REPLACED. THE ACFT WAS OUT OF SERVICE FOR AT LEAST TWO DAYS INVESTIGATING THE AIR/GND SENSING ANOMALY. DURING THE EVENT; IN ADDITION TO THE NUMEROUS WARNINGS; THE ACFT WAS SLOWLY DEPRESSURIZING AS THOUGH IT WERE ON THE GND AFTER LNDG. THE FAILURE OF EMER EQUIPMENT TO RESPOND IS STILL BEING INVESTIGATED.

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.