What must crew members do to ensure the escape slides have inflated correctly?

Crew members must pull the manual inflation handle to ensure that the escape slides have inflated correctly. This action activates the slide's inflation process, which is crucial in emergency situations when rapid evacuation from the aircraft is necessary. The manual inflation handle serves as a backup method for deploying the slide, especially if the automatic inflation system does not function as intended.

The importance of this step lies in the fact that ensuring proper slide inflation can significantly enhance the safety of passengers during an evacuation. If the slide is not inflated correctly, it can impede or prevent a safe exit from the aircraft, making this procedure critical for the crew to verify.

The other steps, such as actuating the emergency inflation system or checking gauges, may also be part of pre-flight checks or procedures after deployment, but the immediate action required to confirm correct slide inflation involves the manual inflation handle.