How do you measure "alarmed"?

I ran across the following news summary on DallasNews.Com: "Passengers on American Airlines Flight 414 became alarmed when they saw parts falling off the right wing and heard unusual noises after takeoff from San Diego on Friday evening."

"Became alarmed"? What does that mean, exactly? If I'm looking out the window of an airplane in which I'm flying and I see parts of the wing falling off I'm screaming as loud as I can "My, g-d, we're all gonna die!" You want "alarmed," I'll show you "alarmed."