Why did American Airlines' expenses spike in early 2023?

American Airlines' expenses spiked in early 2023 due to several factors:

1. **Increase in Flight Costs**: Operating expenses, including flight operations costs such as onboard food, catering, ground handling, crew travel, and airport lounge expenses, increased significantly. This was primarily driven by higher flight costs.
2. **Higher Demand for Loyalty Program**: The growth in passenger revenue was driven by loyalty programs, with record revenue from travel rewards. This indicates that the airline's focus on loyalty programs contributed to the increase in expenses.

In summary, the spike in American Airlines' expenses in early 2023 was likely a result of a combination of increased flight costs and higher demand for loyalty programs.