What improvements did Airbus make as a result of the Air France 447 accident?
The official report has a section headed
5 - CHANGES MADE FOLLOWING THE ACCIDENT
Review of the “Unreliable speed indication” procedure
Flight Operations Telex (FOT) of 9 September 2009 recommending, at the next recurrent
training course, a session on the simulator at high altitude in normal and alternate law
- Manual aeroplane handling,
- Carrying out the UNRELIABLE SPEED INDICATION / ADR CHECK PROC procedure.
Most of the changes were carried out by other parties, Air France, EASA, etc.
If the stall warning didn't stop, but instead changed into an even more ominous "you're now tumbling down at less than 60 KIAS" warning.
Opinion: If the computers have decided they don't know what the heck is happening, it's probably a bad idea for them to make something up at random to shout at the crew. If the computers always know best, they should just probably shut-up, activate the cockpit wrist-restraints and fly the plane.
it might not be out of order for the airplane to announce that it is now very much possible to stall the plane by pulling up (in actual words).
Wild guess: Maybe this would help but not when the PF is already ignoring stall warnings and determinedly pulling up almost continuously. Generally less is more when the crew are likely to be confused and overwhelmed. There's probably a hundred things you can more easily accidentally do when you are flying in alternate law and when you are in alternate law you may not have time to patiently wait and listen whilst the computers enumerate them all to you.
the unlinked nature of the sidesticks was a big part of the problem; are there good reasons to leave them unlinked in future designs?
So that the pilots can engage in wrestling matches? Yes, it seems there needs to be an even clearer indication of conflicting inputs but I'm not sure if mechanical feedback is necessarily the best method. Pilots are already supposed to be trained and tested on clear handover of control.
Linking controls can also cause problems. This was experienced in a Boeing 777 in an incident in Air France flight 011 in April 2022. The pilots thought they had flight control malfunctions but were simply pushing against one another's inputs. Dual input events occur as often in Boeing aircraft as in Airbus aircraft despite linked controls. The AF 011 icident shows that linkage doesn't always make pilots realise that they are making opposing inputs.