In the event of an autopilot malfunction on a long-haul flight, the response of the pilots would depend on the specific situation and the nature of the malfunction. Pilots are trained to handle various scenarios and follow established procedures to ensure the safety of the aircraft and passengers. Here are a few possible actions they might take:

1. Assess the situation: The pilots would assess the severity and impact of the autopilot malfunction on the aircraft’s control and stability. They would refer to the flight manuals and checklist procedures specific to the aircraft they are flying.
2. Engage backup systems: Modern aircraft are equipped with redundant systems and multiple layers of safety features. Pilots would attempt to engage backup systems or alternate modes to maintain control of the aircraft. These backup systems can provide assistance in controlling the airplane manually if necessary.
3. Consult with air traffic control: Pilots would communicate with air traffic control (ATC) to inform them of the situation and seek guidance. ATC can provide assistance, offer alternative routing options, or coordinate priority landing clearances if necessary.
4. Consider diverting or landing: The decision to divert or return for landing would depend on several factors, including the severity of the malfunction, proximity to suitable airports, fuel considerations, and the overall safety of the flight. Pilots may choose to continue the flight if they can maintain safe control of the aircraft manually and the situation does not pose an immediate threat.
5. Crew resource management: The pilots would work together as a team, following crew resource management principles, to effectively manage the situation, share tasks, and make decisions collaboratively.

It’s important to note that autopilot malfunctions are relatively rare, and modern aircraft are designed with redundant systems and extensive safety measures to mitigate such situations. Pilots undergo extensive training and are well-prepared to handle unexpected scenarios, including the manual control of the aircraft if necessary.

If you have any concerns or questions about flight operations or safety, it’s always best to consult with aviation professionals, such as pilots or airline representatives, who can provide accurate and up-to-date information specific to the airline and aircraft type you are referring to.