Sadly, no amount of design can prevent human interaction from defeating the failsafes.
I agree with the sentiment but not the fact. It would be very easy to design a system that totally ignores the human. However conventional wisdom dictates that this should not be the case. The human must have the final say, that is what the regulations say, and so there will always be scope for human error as well as system failure. All these designs have been through massive amounts of scrutiny against these aims.
The idea of combining > 1 independent, limited reliability
sources to improve overall performance is not new.
But to get this to work then the two systems must be 100% correctly characterised otherwise the potential for one to mislead both is always one step away. In fact a modern airliner has systems that can perform a sense - effect loop many 100 times faster and more accurately than a human whilst the human can take decisions that without some very exotic AI the computers can't get close to. Unfortunately the interaction of the two is never perfect and that is what system designers strive for. In this instance I'm not sure the combination of sensors would have made any difference. With the loss of all primary air data, the system would still have to hand control back to the human. The airworthiness authorities basically demand it. In reference to the example, how many combined GPS/Inertial sensors are certified by a civil air authority for navigation?
There other ways to measure air speed, such as the airbus developed
laser measuring system.
Please tell me how. Can a purely laser based system provide a calibrated airspeed? From what I understand, it can tell you how fast the air is moving, but at 37,000ft that is pretty meaningless to the aerodynamics, how does it sense the air density?
With the current design, the 3 pitot tubes are not only of the same type and same manufacturer, but they are also located pretty much in the same place - under the nose...
Placement of the pitot tubes is determined by the need to achieve the most consistent and correct airspeed. The separation is sufficient to ensure they are independent from the point of view physical damage. However icing is and always has been a problem. That is why they have heaters in them. But it is possible for nature to throw something at you that is beyond that capability. No matter how you separate them they will always be subject to icing.
To me there are many lessons to be learnt. Perhaps in the event of unreliable airspeed the AoA indication should become more prominent. Perhaps the stall warner inhibition should only be below a certain radio altitude. Perhaps, perhaps, perhaps. There are perhaps 100s of improvements that can be made, but each one must be considered and the impact on all phases of flight and all types of operation must be analysed before implementing them. I can't subscribe to the idea that the current design is somehow "incomprehensible" or "technically flawed" it is fairly standard from what I see, and follows well established principles. We shouldn't look at one small sub-set of operation and criticise it in isolation, or try to correct it without considering the effect on the whole system. In my opinion, the overall system failed catastrophically because of poor interaction and breakdown of communication between the aircraft and the pilot, the causes need to be established and corrected without introducing more dangerous failure modes.