Aviation communication refers to the conversing of two or more aircraft. Aircraft are constructed in such a way that make it very difficult to see beyond what is directly in front of them. As safety is a primary focus in aviation, communication methods such as wireless radio are an effective way for aircraft to communicate with the necessary personnel. Aviation is an international industry and as a result involves multiple languages. However, as deemed by the International Civil Aviation Organization (ICAO), English is the official language of aviation. The industry considers that some pilots may not be fluent English speakers and as a result pilots are obligated to participate in an English proficiency test.