Which condition would NOT allow for an SIC to operate under normal regulations?

The choice indicating ground icing conditions is correct because such conditions can significantly increase the risk associated with aircraft operations. When icing is present on the ground, it can affect the aircraft's performance during takeoff and landing phases, as well as during taxiing. Under regulations, specific guidelines state that additional considerations and precautions are needed when the flight is potentially impacted by icing.

On the other hand, clear weather with visibility over 5 statute miles is a condition that usually permits normal operations, as it suggests favorable visibility for flight. Night operations, while presenting their own challenges, are still permissible under normal regulations as long as the crew is properly trained and the aircraft is equipped for such conditions. Flying the latest model aircraft is also not a limitation; it generally indicates having access to more advanced technologies, which can enhance operational safety. Therefore, ground icing conditions present the unique challenges that do not allow for normal SIC operations without taking additional precautions.