Final answer:
During takeoff, the ENG MODE selector is set to IGN to ensure that there is a reliable source of ignition in the engines.
Step-by-step explanation:
During takeoff, the ENG MODE selector is typically set to IGN (Ignition) in an aircraft. This is done to ensure that the engines have a consistent and reliable source of ignition throughout the takeoff phase. By selecting IGN, the igniters are activated, providing a spark to ignite the fuel-air mixture in the engines, enabling proper and stable engine operation during takeoff.