[Zhang Fei]

So, make it three codes: the pilots' code, the cabin crew's, and a duress code. Punch in the duress code, and the other codes stop working, and the transponder automatically squawks the hijack code. Maybe the tradeoffs chosen in response to 9/11 are now inappropriate. Maybe suicidal pilots are now the greater threat. Other than the occasional nutcase, easily subdued by passengers and crew, have there been any serious attempts to take over a cockpit since then?

If more of these incidents occur, they will have air marshals on every plane with codes to override pilot attempts to lock themselves in.

[ROCKLOBSTER]

The air-marshals should ride in the cockpit.