If an uncommanded signal is sent to retract or extend the flaps it could be from an external source or it could come from the computer. In the former condition it is assumed that the command sensor unit is in the off position and in this case the computer is off and therefore can’t correct for the erroneous signal. In the latter if the signal is generated by the computer it is assumed to be a valid signal and therefore the computer will not respond. Another point to consider is that not all signals are electrical in nature.
