2024-03 · NASA ASRS report 2101038
B777 First Officers reported anomalies with Air Data Computers; Electronic Engine Controls; and auto-flight functions prior to level off at cruise altitude. Aircraft had a history of these problems and since crew was unable to verify correct altitudes with ATC in RVSM airspace they elected to return to departure airport.
I was pilot flying. On climb out around FL280 we received EICAS messages for No Land 3 and No Autoland. Next we're messages for EEC (Electronic Engine Control) L and R. Following the ECL (Electronic Checklists) checklists for the abnormal procedures; I turned off the autothrottles but decided to wait until level off to disconnect the EECs per the checklists. Leveling off at FL330 I brought the throttles back but the airplane would not level off. I disconnected the autopilot; leveled off at FL330 and re-engaged the autopilot in altitude hold mode. When we had finished the checklists I tried to return to VNAV but it still wanted to climb away from 330; which was still the selected MCP (Mode Control Panel) altitude. Then ATC told us we were not holding the correct altitude as they showed us at FL228. We requested a block altitude from FL320 - FL340 and got it. At this point we also had messages for ADC L; C and R; and knew we had a problem with the airplane knowing what altitude we were at. I suggested we try VNAV again. Once again it climbed away from the MCP altitude but leveled off at FL332. Now ATC told us they showed us at FL330. We were now concerned about our legality for both ETOPS and RVSM; and we called dispatch for consultation. In talking with our dispatcher; the Flight Duty Officer; and Maintenance Control; and also reviewing the maintenance history on the airplane; we confirmed it was a recurring problem. We looked into all other possibilities including talking to a B777 tech pilot; but could get no better guidance on how much the aircraft capability was degraded behind the scenes. We decided the best course was to return to ZZZZ airport. We advised ZZZZ control and returned to ZZZZ; using block altitudes on the descent to ensure no altitude conflicts. At lower altitudes our altitude system seemed to indicate correctly and we landed in ZZZZ with no further issues.Cause: Aircraft system malfunction. Suggestions: Fix the problems with this aircraft.
Air turn back ZZZZ airport performed due to multiple aircraft systems malfunctions. Due to the failures; the aircraft was unable to precisely hold altitude; and was therefore not capable of RVSM and ETOPS operations. Block altitudes were assigned; and ATC was advised since we were unable to accurately verify our altitude. Cause: Due to multiple systems failures; this aircraft was incompatible with RVSM and ETOPS operations.
More incidents for this aircraft family
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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