Spirit Airlines is expecting a wider loss for the last quarter due to revenue falling short of expectations. The budget airline anticipates a loss between $160 million and $173 million, compared to the previous estimate of no more than $145 million, with sales of $1.28 billion instead of the anticipated $1.32 billion. Non-ticket revenue, including fees, was lower than expected per passenger. The company's shares dropped by 6% after this announcement. Spirit and Frontier Airlines have restructured ticket sales by offering bundles that include amenities previously sold separately. Despite facing challenges like an oversupplied domestic market and grounded aircraft due to engine recalls, Spirit remains optimistic about driving improvement in revenue per passenger segment as it progresses with its transformation strategy.