What should not change during a takeoff into IMC according to standard procedures?

During a takeoff into Instrument Meteorological Conditions (IMC), it is crucial that decision speed (S1) remains consistent and does not change. Decision speed is the minimum speed at which a pilot must make a commitment to continue the takeoff after reaching that speed, or to abort the takeoff if it is not feasible to continue safely. This speed is predetermined based on aircraft weight, configuration, and environmental conditions, and it provides a clear operational guideline for the pilot in high-stress situations such as poor visibility during IMC.

Maintaining S1 throughout the takeoff ensures that the pilot can respond appropriately without second-guessing or attempting to adjust speeds during critical phases of flight. This consistency is vital for preserving the safety and reliability of the takeoff, especially when visibility is compromised.

In contrast, factors like flap settings, altitude management, and crosswind correction may need to be adjusted based on operational needs and conditions. For example, flap settings could change depending on takeoff performance requirements, altitude management may vary as the aircraft climbs through different flight levels, and crosswind correction is primarily influenced by wind conditions which can vary significantly. Thus, S1 serves as a critical anchor during takeoff in IMC, ensuring that pilots can maintain focus