PCM is more interference resistant than straight FM. It encodes a binary code to it's receiver and is supposedly only interpreted by it's receiver. That does no mean that it will not be "hit" by another signal from a transmitter on the same channel but it is some added insurance. Like was said earlier PCM radios can also be programed for fail-safe features such as throttle cut, elevator slightly up, rudder right or left, it the case of a signal interruption. Given the choice, I would always buy a PCM radio to have the choice of FM or PCM even if I never used it. They cost more though.

Andy