Under which conditions must a Flight Engineer remain at the FE panel with their seatbelt fastened?

The suitable conditions for a Flight Engineer to remain at the Flight Engineer panel with their seatbelt fastened specifically include takeoff, climbs, descents, and landing. During these critical phases of flight, the role of the Flight Engineer is vital for monitoring the aircraft’s performance and systems, as well as making quick adjustments if necessary.

During takeoff and landing, the aircraft experiences varying speeds, configurations, and potential emergency scenarios where immediate action might need to be taken. In climbs and descents, critical performance parameters must be closely monitored, including engine performance and system alerts, which necessitate the Flight Engineer being actively engaged at the panel.

While taxiing and cruising are also important phases, they may not require the same level of immediate oversight, allowing for more flexibility regarding the Flight Engineer’s position in the cabin. Therefore, the most critical times when their presence is essential, with the seatbelt secured for safety, are during the more dynamic phases represented in the correct answer.