Final answer:
Soldiers are generally not required to wear combat uniforms while traveling on commercial airlines and may choose or be advised to wear civilian clothing. This policy allows for both the comfort of the soldiers and their security during travel, although exceptions may exist for certain missions or security protocols.
Step-by-step explanation:
Uniform regulations for soldiers traveling on commercial airlines can be complex and vary based on the directives from the Department of Defense and the individual service branches. Historically, military personnel on leave were once required to wear their uniforms partly to be easily identifiable by military police for regulation of behavior; however, this practice also led to servicemen using various methods, such as "locker clubs," to evade these restrictions and wear civilian clothes. In present times, the regulations have relaxed and soldiers are generally not required to wear combat uniforms while traveling commercially. Instead, they may be encouraged to wear civilian clothing for personal safety and security reasons, as being identified as military personnel can make them targets during certain operations or political climates. Importantly, soldiers traveling after certain medical procedures or those that might have interacted with radioactive materials may need special permission to fly on commercial flights, as stated by the LibreTexts™ system.
Regarding the allowance for military personnel to wear combat uniforms on planes outside of specific duty requirements, this can be dependent on the mission and current operation security protocols. For instance, during the announcement of the end of major combat operations in Iraq in 2003, President George W. Bush landed on an aircraft carrier wearing a flight suit, emphasizing his role as commander-in-chief. Nevertheless, this was a special circumstance with specific reasons behind the chosen attire.