What should the first action taken by crew members be when they notice smoke in the cabin?

When crew members notice smoke in the cabin, the first action should focus on fire containment procedures. This is crucial because smoke typically indicates a potential fire, and addressing the root cause can prevent the situation from worsening. By initiating fire containment procedures, crew members can assess the situation more effectively and take appropriate measures to control or extinguish the fire before it endangers passengers and crew.

Implementing fire containment involves gaining an understanding of the smoke's source, ensuring that any potential fuels are managed, and preparing for a possible evacuation if necessary. While other actions, such as investigating the smoke source or alerting passengers, may seem important, the priority must be to contain the fire and protect the safety of everyone on board. Addressing the smoke directly by employing containment measures can prevent panic and allow for a more orderly response to the emergency.