Which of the following could lead to a lawsuit against a pilot?

Flying with an expired license can indeed lead to a lawsuit against a pilot because it indicates that the pilot is operating outside the legal requirements set by aviation authorities. Licensing regulations are crucial for ensuring that pilots have the necessary training, skills, and current knowledge of aviation safety standards. Operating with an expired license not only raises safety concerns but can also expose the pilot to legal liability, as they may be considered unfit to fly. This could result in serious consequences, including accidents or incidents that might harm passengers, crew, or property, leading to potential lawsuits for negligence or breach of duty.

In contrast, landing safely after encountering turbulence, using autopilot during flights, and maintaining regular communication with air traffic control are all actions that demonstrate adherence to safety protocols and established aviation practices. These actions are generally regarded as part of a pilot's professional responsibilities and do not constitute grounds for legal action, particularly if they align with industry standards and regulatory requirements.