Radio interference
...been in the hobby 21 years and i agree with RC Pilot - PCM crashes planes!...
...we used to fly at a soccer field with a high voltage power line and 2-way radio tower close by - i flew Futaba Conquest PPM and my buddy flew Futaba Super Seven PCM...
...if i flew too close to the power lines, occasionally i would get a glitch - it would happen maybe 2-3 times in 30-60 flights - but flying 120 sized glow, my buddy crashed 3 planes in a matter of a couple of months with his PCM system when his radio would go into failsafe - he blamed it on Futaba, i think PCM was the culprit - i had no problem dealing with a momentary glitch but when his radio went into failsafe it was bye-bye airplane...