Who sits in a jumpseat during a flight?

The jumpseat is primarily used by crewmembers and/or an ACM (Authorized Crewmember), which is why this choice is the correct answer. During a flight, the jumpseat serves as a designated seat for essential personnel, allowing them to assist with cabin duties and ensure safety protocols are followed.

Crews, such as flight attendants, utilize the jumpseat during takeoff and landing when they must be secured but are also on duty throughout the flight to help passengers and manage any in-flight service or safety issues. An ACM often holds responsibility for safety and may also perform duties that ensure compliance with regulations and operational efficiency.

In contrast, first-class passengers or engineers do not sit in the jumpseat. First-class passengers are seated in designated, more spacious areas of the cabin, while engineers are typically not part of the flight crew and therefore not assigned a jumpseat unless they possess the relevant qualifications to serve in such a role during a flight. Lastly, while flight attendants do use the jumpseat, they are not the only ones authorized to occupy it, which further substantiates that a broader range of trained personnel, including an ACM, can occupy this seat during a flight.