Who is expected at the airport at this time-correct the pronoun?

In the sentence, "Who is expected at the airport at this time?" the pronoun "who" (the only pronoun in the sentence) is correct.

The pronoun "who" functions as both singular and plural.

In the example sentence the verb "is" tells us that the pronoun "who" is functioning as a singular, taking the place of a noun for one person.

If two or more people were expected at the airport, the verb should be, "Who are expected..."