I demand attention!
I must admit - I've done it! I DEMANDED a cabin crew member's attention on a LH A300 departing FRA for LHR. We were approaching 18 for departure and I could see that the Flaps were fully retracted.
I left my seat and walked back down the aisle to the CC jumpseat.
"SIT - SIT DOWN - SIT DOWN..NOW" she shouted at me.
"LISTEN TO ME," I said, "you must call the flight deck NOW and inform them that the flaps are not extended."
She did.
And the reply came back that at the operating weight, Zero Flap was OK. I have no Airbus experience - obviously!
I felt a bit of a Charlie, but I'd do the same again tomorrow if I thought something was amiss.