Spirit Airlines and Frontier Airlines, despite their merger plans falling through, have made strides in customer service. However, they still rank at the bottom of the 2023-24 American Customer Satisfaction Index Travel Study conducted by CFI Group. Overall, the industry has seen improvements in various aspects, such as baggage handling and cleanliness. The survey assessed airlines based on multiple service metrics, including boarding process and staff performance. Despite the improvements, Spirit and Frontier remain below Allegiant, Southwest, Delta, JetBlue, United, and other major carriers.