Which of the following is NOT a pillar of United Airlines' customer service strategy?

Cost-effectiveness is not considered a pillar of United Airlines' customer service strategy. The focus of the customer service strategy at United Airlines primarily revolves around key principles such as safety, reliability, and innovation.

Safety is fundamental to any airline's operations, as it is essential for building trust with customers. Being reliable means that an airline consistently delivers on its promises, such as schedules and minimizing delays, which is highly valued by passengers when choosing an airline.

Innovation, on the other hand, emphasizes continuous improvement in services and technology to enhance the customer experience. This can include advancements in passenger amenities or upgrading systems for more efficient operations.

While cost-effectiveness is an important business consideration, it does not directly define the core approach to customer service at United Airlines like the other three elements do. Thus, it does not align with the primary focus of delivering exceptional customer service.