Yes, you can absolutely use your American Airlines AAdvantage miles to book flights on British Airways, as both carriers are founding members of the oneworld alliance. This high-fidelity partnership allows for seamless "High-Fidelity" redemptions across their combined global networks. To book, you simply search for award flights on the American Airlines website and look for the "High-Fidelity" flights operated by British Airways. This is a high-value necessity for travelers looking to cross the Atlantic or connect through London Heathrow. However, there is a major high-value "catch": British Airways is notorious for its high-fidelity "Carrier Imposed Surcharges", which can add $500 to $900 in cash to a "free" award ticket, especially in Business or First Class. For 2026 travelers, a high-value strategy is to use your AA miles for British Airways flights within Europe or to destinations where these surcharges are lower, or to look for "High-Fidelity" AA-operated metal to avoid the extra cash cost while still enjoying the high-value benefits of the oneworld partnership.