Redundancy was and is the credo of aviation.
The recent cases with the AOA -Sensors and the Pitot-Tubes show that the redundancy can also become a curse.
From a certain number of identical sensors, the reliability is no longer higher because the processing of the data of these many sensors is becoming increasingly complex.
In the case of sensors relevant to flight, in the case of unclear or deviating sensor values, attempts should not be made to provide the pilots with the best possible data and thus contribute to an accident in the worst case, but the automation should step back from the control of the machine in a graduated form at the request of a pilot.
For the further control of the aircraft, however, the pilot must then have alternative data on attitude, altitude and speed available.
A GPS-based emergency control unit could display the current altitude, the altitude change, the speed and the speed change as well as the direction of flight at a non-interfering position in front of each pilot independently of each other and independent of the actual flight sensors.
GPS is not 100% reliable and at least as far as the altitude is concerned, it is not accurate enough to fly with it. But it is by far enough as a handy tool for a pilot to stabilize a plane in unclear attitude and height and to start the troubleshooting of the actual problem.
GPS can do quite a bit better. Three antenna systems can give you very accurate point, yaw, pitch. roll, and rates of, and a much better altitude than given credit for with high quality units. The data errors from the sats that cause most of the inaccuracy re irrelevant because all three antennas are getting the same data, so errors cancel out. They don't need absolute accuracy. Only position relative to each other.
The laser gyros and accelerometers already on the aircraft already do a pretty flawless job at working out yaw, pitch, roll and acceleration. Much better than a GPS solution. And unlike pitot tubes, they're incredibly reliable, seeing as they are sealed, solid-state devices.
On the speed bit, again, GPS does not give you airspeed. Without some device to measure airflow, you cannot have an accurate airspeed indication. The wing does not care about ground speed.
We can already display the GPS information, by pressing pressing a couple of buttons on the FMS/MCDU. But it isn't very useful as a flying reference. Converting the data to some sort of pseudo-MFD has merit, but again, no airspeed...
To be clear, I'm all for innovations that could improve safety, but unless you can get a GPS unit to magically generate an airspeed figure, I don't see how a purely GPS based solution can be used for backup airspeed information.
Sounds like 73m flight control design is an incoherent mess...
A single point of failure (one failed AOA probe out of two AOA probes) is allowed to propagate failure to system with pitch authority. There is no fault accommodation it seems.
There is AOA disagree warning, but it appears there is no actual proper safety rated correlation check between two AOA channels. In that case single AOA failure causing pitch issue is not even the biggest problem. The single AOA probe failure can become undetected and hence latent failure. When the second AOA probe fails, correlation check (if present) between AOA probes may not catch the second failure. Now you have an undetectable total AOA sensing system failure, no opportunity to accommodate fault!
My gut feel is that you can't keep adding stuff on to a 50 year old design without running into issues.
In AF and this crash it seems as if the pilots are fighting against deeper level automation that they weren’t quite aware of.
While we don't yet know what happened with the Lion crash, let's be clear about AF447 - all those people died because the crew did not follow SOP, totally threw CRM out the window and displayed a shocking lack of basic airmanship . A situation that is commonplace around the World on an almost daily basis and is completely recoverable became a shocking disaster.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo