In what circumstance would a crew NOT use a hand signal?

A crew would not use a hand signal when the employee or light disappears unexpectedly because, in such a situation, it becomes unsafe and ineffective to rely on visual communication. Effective signaling relies on clear visibility and the presence of both the sender and receiver. If the person giving the signal or the light used to convey the signal is no longer visible, it creates ambiguity and could lead to misunderstandings or accidents. This emphasizes the importance of visibility in hand signaling protocols. When clarity is compromised, crews must seek alternative means of communication that ensure safety.