[rainee]

But what if the pilot/co-pilot takes down the flight attendant?

[MichaelCorleone]

-But what if the pilot/co-pilot takes down the flight attendant?-

I don’t think an airline can plan for every conceivable contingency; too costly for one thing. Maybe the flight attendant can have a firearm or taser at the ready.

Or possibly the armed flight attendant(s) can stand by while the door is firmly propped open. Presumably the pilot will only be gone a few minutes.