Abstract: This article is devoted to the peculiarities of functioning composite sentences in English aviation texts. The subject matter of this research is types of complex sentences in modern English and the means of connecting main and subordinate parts of these sentences. Research in the article is done on the basis of scientific and journalistic styles. Special attention is paid to the general characteristics of lexical and grammatical features of these two text styles. In the article, a comparative analysis of different types of subordinate clauses is made and difficulties in translating them from English into Russian are analyzed. In her research, Meldianova applies the following research methods: description used to define, interpret and classify complex sentences; and comparison used to analyze types of syndetic words and subordinating conjunctions in complex sentences. The novelty of this research consists in the conducted for the first time complex study of means of connecting sentences within a composite sentence on the basis of English aviation texts of scientific and journalistic styles.