When is it permissible to transmit messages encoded to obscure their meaning?

The FCC strictly prohibits the use of codes or ciphers intended to obscure the meaning of a message. Amateur radio is designed to be an open, transparent service where anyone can listen to and understand the communications. However, there is a very specific safety and security exception to this rule. Operators are permitted to use encrypted or obscured commands when sending telecommand signals to space stations (satellites) or radio-controlled craft. This prevents unauthorized users from hijacking or interfering with the operation of these remote vehicles. Many learners are tempted to select 'Never' because the prohibition against secret codes is so heavily emphasized in study materials. Distractors regarding 'approved digital codes' are also incorrect because digital modes are designed to format data efficiently, not to hide its meaning.