What does a continuous whistle blast typically signal?

In the context of safety and communication protocols, a continuous whistle blast is often used as a universal signal indicating a need for help or immediate attention. This sound is designed to be attention-grabbing and is recognized across various environments as a call for assistance. It serves to alert nearby individuals that someone is in distress or requires urgent support, prompting a rapid response.

The other options point to different types of signals that typically use varying patterns or types of sounds: a request to move, for instance, may involve short, repeated blasts rather than a continuous one. Similar distinct sounds are used for signals like “start lowering” or “signal clear,” which govern operational actions in controlled environments. These specialized signals ensure that communication remains clear and concise, reducing the likelihood of misunderstanding in critical scenarios.