What should a Plane Captain ensure before launching an aircraft?

Before launching an aircraft, it is crucial for a Plane Captain to confirm that there are no discrepancies noted in the Aircraft Discrepancy Book (ADB). This book is a critical tool that documents any issues or maintenance concerns identified during the aircraft's operation, maintenance, or inspections. Ensuring there are no discrepancies means that the aircraft is ready for safe operation and that all maintenance and inspections have cleared the aircraft for flight.

The absence of discrepancies indicates that no unresolved issues exist that could impact the aircraft's performance, safety, or compliance with operating standards. If any discrepancies were present, they would need to be addressed before the aircraft could be considered airworthy.

While the other choices involve important aspects of aircraft readiness and safety, they do not specifically address the immediate and critical needs of ensuring the aircraft’s airworthiness through a thorough check of the ADB. Fueling, documentation, and crew presence are also necessary elements of the launch process, but the priority lies in confirming that no maintenance or operational issues may hinder the aircraft's performance.