I'll note my concerns point by point

1. Feasable, but I don't know that it will really reduce business trips that much. Too many see the face to face approach as the best way to conduct business.

2. Password protection has an inherant trade off. At some level, you have to either err on the side of "ease of access" or security. Do you set up the protection so that potentially the actual pilot can get locked out, or do you make enough allowances that the terrorrist could potentially hack the system. There is no middle ground, and the best balance is a moving target. The best bet for securing the cockpit would be to firewall it off from the passenger cabin with a separate entry point. This would require provisions attached to the cockpit for food, restroom, and extra crew for emergencies. Of course the next concern is how the food is supplied. If the crew brings their own, and stores it themselves, it should be safe, but if it's stocked by the ground crew that leaves the potential for poisoning. The crew themselves would of course have to be screened, but I would severly hope they are anyway!! I do like the knockout gas idea (in theory) that I read elsewere, but that could be potentially tampered with by the ground crew; either disabling it, or putting it under the control of the terrorrist to use for their own end.

3. If you arm the crew, you potentially arm the terrorrist! This is never a good idea, and is the reason it hasn't been done.

4. This is just an inconvenience. Dying from a terrorrist attack where a weapon got carried on would be more than an inconvenience, so this has potential.

5. So, no Irish? This one has a serious grey area. I understand what you're saying, but it's a matter of where the line gets drawn.

I'm not saying these were bad ideas, just that they do have weaknesses; and terrorrists love weaknesses.