Which code indicates that a passenger uses their own safety restraint?

The code that signifies that a passenger is using their own safety restraint is AMSA. This code is specifically designated for situations where a passenger requires the use of their own safety device, such as a safety seat or harness that they bring aboard the aircraft. By using this code, airlines are alerted to the fact that special accommodations or considerations may be necessary to ensure the passenger's safety while traveling.

Understanding the context of the other codes can clarify why AMSA is the most suitable choice in this scenario. For example, BDGR refers to a passenger needing assistance due to a medical condition, whereas ATO indicates a passenger onboard with a reduced mobility requirement. BBG pertains to unaccompanied minors, indicating their need for extra attention during the flight. These other codes represent different special service situations and do not specifically address the use of personal safety restraints.