American Airlines is a major American airline headquartered in Fort Worth, Texas. It is the world's largest airline by fleet size and revenue and the second largest by number of destinations. In 1967, an Italian artist named Massimo Vignelli designed the AA eagle, popularly known as the American Airlines logo. The "A" word is represented by two capital letters with a stylized eagle positioned in the middle. The AmericanAirlines logotype can be seen below them.
Helvetica Neue Bold is the most likely the font used for the AA monogram and logotype. It is available as a commercial font and you can purchase and download the font here.