How does one secure cockpit doors?

[John Doe II]

Does anybody know here how one does secure acockpit door of a Boeing 757?
The background for this question is that the pilot of UA 93 was warned twice to be aware of cockpit intrusion and secure the cockpit door.
Therefore I'd like to know how one can do that and how difficult it would be to open a secured cockpit door.
Thanks for your help!

[petgoat]

1. Boeing Doors

Go to the message board at Yahoo Finance for the Boeing (BA) stock
discussion. The board is frequented by Boeing engineers and aircraft technicians.

(While you're there ask them if they're familiar with Dr. Jim Fetzer's
book on the Paul Wellstone plane crash and its investigation.)

[philb]

2. I think they can put a bar across them; but irrespective once warned

I don't think a hijacker could get through a locked door without the pilots at least signalling, but also likely taking action with the plane to insure the hijackers couldn't stand up and threaten the pilots.

Col. de Grand-pres group of military and commercial pilots say unanamously that the hijackers could not have taken over in that circumstance.

[philb]

3. 911Research Group: Implausible takeover of flights by the hijackers

Implausible takeover of flights by the hijackers

http://911research.wtc7.net/planes/analysis/pilots.html