High Voltage Power Lines
avoid flying close to them

Single or Dual conversions - it doesn't matter

We have personal experience and that of a few other very experienced R/C flyers confirming that flying in close proximity (200ft or less) to high voltage power lines will cause radio interference. It appears that the more complex the radio installation is, i.e. lots of servos and extensions as in most jets, the more likely the problem.
Flying low with the power lines between the transmitter and the model is similarly dangerous. If a power line is buried in the ground, low passes over it can result in severe interference.
An RF engineer confirms this reality and added that if climatic conditions are especially humid, the problem is accentuated.