B737 Undifferentiated or Other Model
Flight Crew Last 90 Days 10; Flight Crew Total 15651; Flight Crew Type 6113
Aircraft Equipment Problem Less Severe
Aircraft
Aircraft had deferred INOP (Inoperative) autothrottle as of date. Defect writup included 'autothrottle disengages automatically repeat gripe. Occurred after T/O (Takeoff) autothrottle disengaged. VNAV (Vertical Navigation) failed. No N1 (Low Speed Compressor and Turbine Spool) limit display.' Writups on date also included 'EGT (Exhaust Gas Temperature) 930 in caution for 3 seconds max power T/O (Takeoff). N1 set 102.4' with a similar information only report adding 'TAT (Total Air Temperature) was -74 in climb.' Significantly differing (R vs L) wind information was also included but missed by me in my review of the writeup: 'WIND L/069/256 RT 060/21'I signed for the aircraft while we did not fully understand the implications of the relationship of the gripes. I believe that the puzzle pieces were in the writeups for Maintenance and/or us to not accept the aircraft as unable-to-operate. The writeups were not clear however and either left out the full impact of the missing performance information or any transient (assumed) vs remainder of flight nature of the gripes. After takeoff; VNAV failed and was not able to be activated for the remainder of the flight. TAT showed approximately -70C in climb. Not only were the N1 limits not displayed; but the FMGC (Flight Management Guidance Computer) would not provide N1 limit information. Progress page 2 SAT (Standard Air Temperature) reading was blank. There was no actual SAT or TAT information available. At thrust reduction altitude; I called 'set climb thrust;' which began a frustrating search for climb thrust information. I pulled the throttles back to a conservative thrust setting below a realistic actual climb thrust; while complying with all climb performance requirements. We were at approximately 15;000 ft; and climbing as we came to fully understand that we did not have any actual TAT information and therefore insufficient information to enter the MAX CLIMB %N1 chart on FM 5.60.1. We planned a strategy to continue to ZZZ1 safely and considered destination weather; divert option weather; enroute weather including the low probability of mountain wave with our lightly loaded aircraft. We were also ferrying fuel giving us some confidence given that all the fuel calculation functions of the FMGC were unavailable. Conservative climb thrust settings were used and a lower planned cruising altitude of FL370 vs FL390 was selected for buffet margin. Dispatch reported forecast SAT for our chosen altitude and flight path which we converted to TAT with conservative margins added for a climb N1 limit at cruise. Two pilots with significant experience with the 737 were a factor in our decision to continue. Dispatch and Maintenance Control were advised of our limited performance capability. It was noted at cruise that the wind information displays and TAS (True Airspeed) indications left vs right were not consistent. Flight plan winds never exceeded 40 knots; while the captain's side displayed a 344 knot tailwind at one point with an 84 knot tailwind displayed on the right. TAS indications were inconsistent by at least 50 knots. A G/A (Go-Around) thrust was calculated for our approach and landing; bugs set manually; using ATIS (Automated Terminal Information Service) arrival temperature. Note that at no time were indicated airspeed indications (left / right / standby) ever inconsistent or incorrect. At no time was thrust in any way limited if we needed it; we conservatively limited N1 by a few percent in climb and we carefully calculated a limit in cruise and for go around.
B737 Captain reported numerous anomalies with the Flight Management System.