Which of the following is the only permitted case when transporting a firearm on an airplane?

When transporting a firearm on an airplane, the only permitted method is using a lockable firearm case. This requirement stems from safety protocols designed to prevent unauthorized access to firearms during transit. A lockable case ensures that the firearm remains secure and that only the owner or authorized individuals can access it. This is particularly important in an airport setting, where there are numerous security concerns.

Additionally, regulations from the Transportation Security Administration (TSA) mandate that firearms must be unloaded and placed in a locked container that is not accessible to anyone other than the owner. Choosing a lockable firearm case helps fulfill these legal requirements while ensuring that the firearm is adequately protected during transport.

Other forms of packaging, such as a soft case, hard shell case, or a regular suitcase, do not meet these criteria since they may not provide the necessary security or unavailability to unauthorized individuals.