Greasy Monkey
The autopilot system having the ultimate control over the door lock - whenever pre-set deviation limits for the flight controls are exceeded, the door is unlocked....
These deviation limits should be set according to the flight plan/route (automated calculation of % deviation, or similar), and if they are to be over-ridden, require two valid pass-codes from the assigned crew.
Great
...so how would that work if one of the pilots becomes incapacitated and the other pilot decides to initiate an diversion to an en-route airport? He/she might be OK with the door becoming unlocked, but he/she and perhaps the Feds might not be...How would it work if you had to engage in serious weather avoidance - in addition to doing the weather avoidance, liase with ATC/cabin crew, etc, you've now got to enter (repeatedly?) codes? A "simpler solution" it is not....
1201
To bring a flight attendant upfront creates many other issues.
Agreed. If not done properly and with great care it certainly has the potential to create serious problems, and no, I'm not going to spell them out here.