I had a crash with my E-Flite Beaver that was a real cause for concern. I was flying along great and then lost all control of the plane. With DSM2 and a JR9303 DSM TX I thought loss of control were a thing of the past. But I learned that my mistakes can add up and lead to a crash.
I used a battery that had been in a minor crash. Sure it held voltage but it would react under load differently than a healthy battery. Flying with this battery and a ESC BEC driving 6 servo's and a 9ch DSM2 RX = brown out
Not binding my TX to RX after setting up the plane. You can see what the fail-safe location of your servos are in on a DSM2 RX when you first turn on/plug in the battery to the RX. For a second the servos go into their fail-safe mode and then the TX takes over. Well in my case the servo for the flap and aileron were still at Gear and AUX1. That's full throw.
After crashing I didn't know that I could read the led light on my RX to tell me if I experienced a brown out. While I know what happened it would have been nice to have actual proof.
I rebuilt my Beaver and flew it today with new batteries. It actually looked and flew great. When it first hit the ground I wanted to toss it in a barrel but now you'd never know it was in a wreck.