Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of unmanned aircraft maker and Motley Fool Rule Breakers pick AeroVironment (Nasdaq: AVAV) fell faster than a drone shot from the sky today, dropping 12%.

So what: That isn't exactly what happened, but one of AeroVironment's test unmanned aircraft did go down during an extended test flight. The Global Observer crashed at 2:30 PT this morning, 18 hours into its ninth test flight.

Now what: The market may be freaking out, but I don't see this as a huge negative long term for AeroVironment. The aircraft is testing new technological boundaries and glitches are to be expected, although this isn't the kind of learning experience designers were hoping for. And on the plus side, no one was hurt in the accident over Edwards Air Force Base in California. I'm not selling my shares today and think this will be a blip on the screen over the long term.

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