Flight engineers have an extensive list of roles both on and off the ground. Before takeoff begins, they must inspect the aircraft and ensure that it is safe for use. They often have a pre-flight checklist that has to be completed before a plane is cleared to fly. These include checks for any fluid leaks or improperly inflated tires.

Once the plane is airborne, the flight engineer constantly monitors all of the computer systems and checks for any abnormalities. They are experts on all of the plane's mechanical instruments including the fuel gauges, pressure indicators, wing flaps and even the landing gear. The pilot can confer with the flight engineer if they have any questions or concerns about a specific instrument and its operation. They also take a look at the weather patterns and determine the proper amount of fuel required for the flight. They control the air conditioning, cabin airflow, the main electrical system and the engine power. Flight engineers are constantly collaborating with the pilot, determining if any specific adjustments need to be addressed. Many flight engineers have their pilot's license and could potentially fly the aircraft if absolutely necessary.

Following the flight, they do a thorough inspection of the plane and ensure that all components are functioning properly. They must also submit a completed flight log of the trip. If a problem did occur during the flight, it is their duty to file a proper report and to contact the mechanics for repairs.