You need a door good for at least five minutes, which should give you enough time to get out those Uzis loaded with frangible bullets. <img src="mad.gif" border="0"> And in the meantime you can dump the cabin so nobody will be standing unless they've got portable oxy.
As I've said before, you really need TWO strong doors to protect against a suprise strongman rush. The space between must be clear of passengers and the outer door secured whenever the cockpit door is opened.