Which type of operational notification involves readiness for engine start or taxi?

The correct answer pertains to the operation of anti-collision lights and landing/taxi lights being illuminated. This practice is critical for ensuring that an aircraft is visible to others as it prepares for engine start or taxiing. By using these lights, the crew communicates readiness to both ground personnel and other pilots, indicating that the aircraft is about to become active and may move.

Operational notifications are especially important in busy airfield environments, where multiple aircraft, vehicles, and personnel are interacting in close proximity. The use of anti-collision and taxi lights serves as a visual cue to enhance safety, helping to prevent accidents by making the aircraft more conspicuous to anyone in the area.

While the other options may involve signaling or communication in some capacity, they do not specifically relate to the operational readiness signified by the activation of lights as part of the aircraft's pre-taxi protocol.