Does aircraft require national colors to be displayed?

Answer 1

Military aircaft display national markings in order to be identified by other aircraft as enemy or friendly. Modern US Air Force jets use markings that lack color and are shades of the camoflage. Civilian aircraft are only required to carry a Registration identification number. This registration ID includes Letters and Numbers and each country has a unique prefix Letter(s). For example, all aircraft registered within USA begin with "N" and this registration is commonly referred to as the "N-number". However, I do not think a civilian aircraft is required to display the national flag.