Yes, in this sentence, "it" refers to "an aircraft, bird, or insect." This type of pronoun is called a singular indefinite pronoun, which means it can refer to a non-specific noun in a singular form. In this case, "it" is used as a pronoun to represent any of the three options mentioned: an aircraft, bird, or insect. The pronoun "it" allows us to avoid repeating the full noun phrase each time.
