For which situation should crew members prepare a ditching briefing?

Crew members should prepare a ditching briefing specifically when flying over large bodies of water because this scenario presents a higher risk of needing to execute an emergency water landing. In such situations, it is crucial for the crew to have a clear plan and to communicate necessary procedures to ensure passenger safety. This briefing includes important information about the use of life vests, procedures for opening doors and exits in a water landing, and the locations of floatation devices.

The other options do not represent situations where a ditching briefing is as critical. For example, flying at night might pose visibility issues, but it does not inherently increase the risk of needing to ditch. Turbulence can affect flight stability but does not necessitate a specific ditching strategy unless it is combined with other emergency situations. Approaching the destination airport typically involves preparing for landing procedures rather than a specific focus on ditching, as landing on land is the standard expectation.