Sorry Mode One but yours is a popular misconception about PCM. If you get interference on a PPM system its true that you can "fly through it". With PCM each frame is transmitted as a string of numbers with a check sum tagged to the end of the frame. A simplified explanation would be if the numbers when added up would be even then the check sum would be 0, if when added up they would be an odd number then it would be one. (this is a simplified explanation but the same principal applies to computer network frames) The reciever the performs the same known calculation on the frame and compares the result to the checksum digit(s), if its the same it passes the frame for processing, if its different it discards the frame. If its some sort of intermittent interference you would probably never know if it dropped a few frames here and there whereas PPM may give a small glitch. Now then, if a given number of frames in a row are bad then PCM goes into lockout and drives the servos to their fail safe point. Here's where you are incorrect in your assumption, as soon as the reciever decodes a good frame you instantly get control back if or until you get another preset number of bad frames. So.....if the interference is bad enough to cause ppm glitching or loss of control all the way to a crash then its likely that pcm will stay locked out all the way to the ground, an example of which is someone turns on and leaves on another transmitter on the same channel. The only difference is that the PCM one, if the person took the time to program the fail safe (not always the case), will hit the ground with the throttle at idle. If its intermittent interference a pcm flyer may never know, such as a bad bearing, until its bad enough to cause constant interference and lockout.