Air Asia Indonesia Lost Contact from Surabaya to Singapore

[Australopithecus]

Heavy Metallist: bravo.

There are problems with protections and envelope constraints: they rely on fallible sensors for their information. So, back to "Data Processing 101" : Garbage In= Garbage Out. True in 1971, doubly so now.

For the uninitiated- the aeroplane relies on its flight control software to implement the control laws complete with protections to address the needs of 99.99X% of all flights. On a very very few flights the sensors get compromised, all of the laws, protections and load relief goes away and the now betrayed crew is left with a lightweight, flexible, undamped aeroelastic, auto trimming nut case with a one-eyed determination to save the day by diving or stalling the aeroplane into the ground.

Bad sensors. Like bad rumours, mixed up lab results and WMD intelligence, they lead to grave misjudgements and irrevocable error. The problem of an uncrashable aeroplane is the same as an unsinkable ship: The crew has to politely smile at the marketing, understand its limitations and, if called, be able and willing to step up and act like an old fashioned master, not someone who is just along for the ride. (EMPHATICALLY NOT SUGGESTING THIS IS THE CASE WITH THE ACCIDENT FLIGHT, by the way. But I suspect that it is an industry problem. )

The flight guidance system at this stage is too rudimentary to provide guidance out of unusual attitudes. That's the stuff that we are supposed to be experts at after 15 or 20 minutes of training every couple of years. Oh...and the mythical aerobatic experience as a teenager followed by the fighter training and pylon racing, I guess.

Since recovery from inappropriate energy states and attitudes is actually pretty binary it might be possible to quickly develop a recovery guidance mode to facilitate the lowest common denominator crew** to follow prompts or director cues to the correct attitude to regain normal flight paths and loads. That would be the missing half of the promise that fly-by-wire makes: (This aeroplane is not stallable. If, however, you do stall it, it will tell you how to undo your error)

**: this is relative, obviously. Any one of us could be the lowest common denominator depending on skill, experience, fatigue and other intangibles on the day.

To recap:
1:FBW is a huge improvement on the pieces of sh1t that I used to fly when I was a zygote. So is almost everything else
2:FBW has probably reduced the incidence of serious incident by at least an order of magnitude. (And hence the accident rate is equally reduced)
3: Auto flight, at least on the approach, is not as smooth as the hypothetical experienced, well rested crew.
4:Like all numerically controlled machines, modern aeroplanes rely on sensors. Lots of them. They are lightweight, built to a price, and they fail from time to time.
5:Spurious warnings, cautions and whatnots are far more common that real ones.
6:Spurious alarming data is not immediately distinguishable from actual alarming data.
7:Active protections can save passengers from random dumb crew mistakes.
8:Spurious protection triggers can expose passengers to random dumb designer mistakes. (Too trusting of sensors without appreciating the "what if" hypothetical scenarios. Which happen from time to time)
9:"Golden Rule" instructions are all predicated on the presence of a very experienced, jaded yet competent crew to fly manually like a conventional aircraft when any unexpected or sub-optimum performance is demonstrated by the automatics, however subtle.

On edit, added: 10: the altitude capture mode, called "Alt star" presents peril when it engages during a high rate of climb manoeuvre. It locks in the current rate of climb, in this case, if it engaged, at over 1000 ft below the target altitude. If the wind shear dissipates and or the updraft fails, the aircraft will be left with a rapidly decaying airspeed and an autopilot disconnect at high alpha.

(At my peak I used to manually fly 1000+ hours every year. On raw data. While doing star shots and smoking black coffee and drinking unfiltered Luckies. And listening to disco music on the ADF receiver. While keeping an eye on that pesky number 13 cylinder on number two.

Today I get about three minutes of manual flying per week. I am considered a thrill-seeker for doing that much. Incredibly, an entire industry has grown on the convenient lie that the old skills, if ever attained, remain honed after decades of neglect.