Departure procedures are based on what aircraft operating conditions?

Departure procedures are primarily based on the conditions of the aircraft when all engines are operating. This is considered the standard scenario for most departure operations, as it reflects the aircraft's maximum performance capabilities. When all engines are functioning normally, pilots can rely on the specified configuration, speeds, and clearances outlined in the departure procedures which ensure a safe ascent and adherence to air traffic control protocols.

In this context, the procedures are designed to provide optimal safety margins and performance guidelines to navigate safely during the initial phase of flight. Utilizing procedures predicated on all engines operating also establishes a consistent framework for pilots to follow under typical operational circumstances.

While the other choices involve critical considerations, such as engine-out conditions or emergency procedures, these scenarios apply to specific situations that deviate from normal operating parameters. Departure procedures written for conditions where all engines are operational are foundational to aviation safety and operational efficiency.