3.1 Whistle signals are a simple and effective means of communication between rescuers and those operating a rope-raising or rope-lowering system. They may be used as a primary means of communication or as a backup when radios fail or when ambient noise makes them unintelligible.

3.2 These same signals can be used in non-rescue situations, for example, by persons rappelling in caves.

1.1 This guide covers the methodology for the use of whistles as a means of communication during rope rescue operations.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.