If this has been answered please point me to a post number.
The news reports have said that after the pilot left the cockpit , the copilot then locked the door and pressed 'the button' that set the autopilot to 100 feet. How can that specificity be deduced from just the CVR? Is there an audible confirmation of that setting?
Jay, no there is no one "button". This seems to me (the report that you heard, and are now relating) to be speculative. Perhaps "simplified" in order to make it readable by a lay audience. (?)
Operating the A/P ("Auto Pilot") is usually not loud enough to be picked up on the CAM ('Cockpit Area Microphone'). The basic procedure to change altitude, when on A/P is to rotate a knob (it has "clicks" or detents, but this is primarily for tactile reasons....the setting on the display is what's referenced). After inputting a new altitude then certain other buttons can be depressed, but again....these usually are nearly silent. the Flight Data Recorder's info will provide a time-based corroboration of the series of events, including the operation of the Auto-Flight controls.
I just found this video....am a bit dismayed that is is public (It seems to have been produced as crew-member training), but now is public:
(Please note that the video above may or may not be pertinent to every airliner, and every airline company. It is ONE example of a product that was available for an airline to purchase, and install on their Airbus aircraft).
Found the above video whilst searching for operation of the Airbus A320 'FCU' (What Boeing terms a 'Mode Control Panel', or 'MCP'...similar function and operation, just different way to use terminology).
If I may be indulged with one more video? (And I'm sure that TWCobra, with a lot more experience IN Airbus products, can be asked about it)...this is video shot in an actual A320, as compared to a simulator or a even a home-based set-up (many videos of those exist as well):
Note, please, the typical "background hiss" (my term..."hiss") on the Flight Deck. At about 0:35 the Captain is touching, and changing the 'FCU'....that's the array of controls just under the glareshield. These are the main ways that the Auto/Flight systems are controlled, and inter-acted with.