Originally Posted by
olster
Fdr you really nailed it. The 737 as you are well aware has a large powerful stabiliser attached to a small elevator. I have anecdotally seen in the simulator a stab runaway that would have had a catastrophic outcome due air loads if it were not for the timely press of the freeze button. Assuming of course that the sim is programmed to match the aircraft. The fact remains that if your stab runs away at the wrong energy level and you don’t catch it swiftly you could get unravelled real quick. This is regardless of how the stab runs away, MCAS or not this is an Achilles heel on type that remains in a corner of the envelope that I hope nobody finds. Bring on the narrow body mini 777 with full fbw would have been my original advice prior to the tragic accidents and remains so. The Max fiasco is a stain on Boeing which they have to live with and move on from. The fact that executives with large and unimaginable pay have come through this unscathed while functionaries are pursued is beyond shocking. The one source of alpha in defiance of basic engineering principles coupled with the lack of prescription on MCAS to pilots still defies belief.
The B737 is well past its use-by date. The grandfathering of 1960's rules has been stretched pretty damn far.
A circular fuse that takes LD3s would be a starting point. The control laws of the B777 & & 787 are really a mixed bag of goodness. The absolute safety level of the
C*U is definitely attractive, but when driving the plane, the
C* Airbus normal law is a delight. The Airbus laws get a bit odd around the crosswind takeoff and landing phase, but that is not something that can't be improved on with some logic. The amount of switching to force the control laws to revert to alternate or direct is pain on an Airbus, the single switch in the Boeing is a simple manner of getting rid of most if not all of the anomalies.
The
U term of the Boeing keeps the crew in the loop with the stabilizer setting, it is the speed reference value that is being set for the flight control system, which means the driver is on the trim all the time in manual flight. The A3xx events of upsets almost invariably involve the change of laws that the crew then have being unable to comprehend that they need to move the manual trim wheel. That is the downside. Upside is when working it does exactly what a pilot wants with an effectively well-damped yet neutral stability pitch law. The fact that Boeing FBW has a phugoid due to the
U term is just an irritant, as is the philosophical curiosity that manual flight with the ATR engaged can give essentially a FD in speed mode and the ATR in speed, so they can get out of sorts and cause the driver to flop about the sky a bit. It is below the importance of the coffee cup holder, but it is there.
So control laws wise, the Airbus is nicer to fly in normal mode, and without a great crosswind. Have a fault, and the Brand B system has maintained the driver in the loop, [HMI: D.I.T.L] Why "driver"? If the Pilot-in-command forgets to rotate the aircraft 'cuz the FD is not pointing upwards, it is hard to use the term pilot anymore, it is more a driver, a person who has a certificate of some form that permits them to sit in the seat, competency being apparently an arbitrary requirement any more.
Oh yeah, putting enough wing and flaps and LEDs to get the Vappr down below Vmo would be a great thing too. Was always amazed that my B744s had lower approach speeds than the B737. The number of overruns per sectors flown per type speak for itself. Having a low Vs1g is a safety matter, worth the~ 2% of structure that the flap system costs to the plane.