B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Inflight Event / Encounter Other / Unknown
Flight Crew Took Evasive Action
Aircraft
I am curious to know what the cost would be to procure better LNAV/VNAV/Autothrottle software for our B-737s. Although we can and do fly the aircraft safely; the current software does not provide a smooth flight for our Customers during climbs and descents; and does not preclude costly overspeeds of our flaps. We have been told that not raising the flaps up prior to 230; it can result in an inspection costing $500;000. I would say we could purchase a much better software package and utilize VNAV for that $500;000 (times however many overspeeds occur per year). Yes; we are expected to prevent such overspeeds and not rely on automation; but by that logic; why do we have a gear or configuration horn; when we are expected to properly configure as well? The -700 is not immune to our poor software either. I find it embarrassing when our aircraft levels off during a climb because it is two knots slow; then performs an aggressive pull up followed by slightly negative G pushover when attempting to climb to cruise altitude.Additionally; I was cruising at our optimum altitude of 39;000 ft with .785 as ECON Cruise; without encountering Mountain Wave; the aircraft accelerated close to .82M; which we took action to prevent an overspeed; then decelerated to .71M; close to Min Maneuver at high altitude. (I wrote up the autothrottle system on this aircraft). Our new ECON Speeds have us cruising and descending at high Mach speeds; resulting in overspeeds and/or the use of speedbrakes during a VNAV descent; despite inserting the Forecast Descent Winds. This is unacceptable and can be fixed with a better software package; which can be offset with the decrease in overspeed inspections.
B737 Captain described over speeds during VNAV arrivals and departures caused by FMC software and believes that updating the software would be less expensive than over speed inspections and smoother for the passengers.