relaxed static stability
Thanks for finding that pearl about the static stability, Retired. Thank you, thank you.
For those that have not flown a FBW system that has "limits" or "protections" embedded in the flight control laws, you are only commanding control surface deflections when rotating on the the runway to get airborne. So if the system is using gee as the primary "command" or even "limit", then the elevators could be moving all on their own despite your stick inputs to achieve that gee. This is a player when at a steep climb unless the system compensates for the pitch attitude ( as the 'bus does in Normal law). The system will move the elevators and THS to achieve 1 gee, but you really should be commanded less than 1 gee. For example, at 30 deg of pitch we should be holding 0.87 gee to maintain a 30 deg pitch while climbing ( honest, the VooDoo required that until about 25K when in an afterburner climb). If you command 1 gee, then you continue to increase pitch attitude.
And now, Airbus shows us that the jet DOES HAVE a point on the pitch coefficient curve that is "neutral". It's why I jumped in here initially to show that the Viper has such a point and we didn't find it until well into the program. But the combination of relaxed static stability and the control laws ( gee command and AoA function) allowed us to get to a deep stall and stay there with hands off the stick. We got there by doing exactly what AF447 did - climb at a sufficient angle and power setting to run outta energy/aerodynamic effectiveness of the elevator before the system could get the nose down. I posited this scenario the instant I saw the graphic of the wreckage. Looked like a classic deeply stalled jet pancaking into the water at a high, very high AoA.
The BEA comment about positive static stability and stall entry was a good one. Before FBW, it worked. You had to work hard/pull hard to get to the stall. Let go and most planes would pitch nose down to achieve the trimmed AoA. But the FBW systems will allow you to get to the stall if the laws are heavily biased for gee command, and do not blend in AoA, pitch rates and so on.
The second "aha" for me was the buffet values were established. Certainly high enough for most pilots to realize that something was wrong, as in an approach to a stall. Before this, I felt that the jet was so smooth that a stall entry buffet was too low to provide a tactile warning. Personally, a buffet of 0.1 gee Nz seems adequate to provide a warning without any fancy chimes/clangs/etc. And a buffet much higher than that once in the stall should have been a very big indication of what the jet was doing.
The good news is that we can train to handle the situation, even prevent the situation.
I would also like to see Airbus use the AoA in conjunction with the gee command to keep the jet from trying for gee "uber alles". This is in alternate laws, as the thing seems to do this in Normal.
The air temp and ozone stuff seems irrelevant other than distracting the crew. And an apology to OKie. I wanted to fly the F-4 when it first came out, and even a C-130 if I couldn't make the cut for fighters. Nevertheless, I never wanted the degree of responsibility required to get a few hundred folks to their vacation venue, so took a pass on an airline job once outta the fighter community. If I screwed up, then it was my skinny butt and not a slew of others. Just my personal philosophy, and no offense to all here that have accepted the responsibility and have survived along with their passengers.