What must a flight crew comply with if ATC does not specify a departure procedure prior to takeoff?

A flight crew must comply with the departure procedure established by the FAA if Air Traffic Control (ATC) does not specify a departure procedure prior to takeoff. The FAA sets specific procedures to ensure the safety and efficiency of air traffic operations. These procedures are developed based on safety assessments, operational requirements, and other regulatory frameworks that govern aviation practices.

When a flight crew is unsure of the appropriate procedure, referring to the FAA-established procedures provides a standardized approach that all flight crews can rely upon. This consistency is crucial for maintaining safe and orderly air traffic, especially in busy airspace. The choice of procedures ensures that pilots are operating within the guidelines established for their respective airports and airspaces.

In contrast, other options may not offer the same level of regulatory oversight or standardized safety parameters, making them less suitable in this scenario. Hence, following the FAA's established procedures ensures compliance with national regulations and promotes overall flight safety.