What should agents do before entering an aircraft?

Before agents enter an aircraft, obtaining permission from the pilot is crucial as it ensures safety and coordination. The pilot is responsible for the overall safety of the aircraft, and communication with them is essential before any personnel approach or board the aircraft. This step is part of standard operating procedures to prevent any accidents or miscommunications that could compromise the safety of the ground crew and the aircraft itself.

Additionally, the other options, while important in their respective contexts, are typically conducted in conjunction with or after the pilot's clearance. Checking for visible damages, performing a safety briefing, and securing ground equipment are all necessary steps that contribute to overall safety but should follow the primary communication and permission granted by the flight crew. This systematic approach helps maintain a safe working environment around the aircraft.