American Airlines is offering a mid-contract raise of up to 8 percent to its pilots and flight attendants after mounting tension from their respective unions.

In a letter distributed to employees and filed with the Securities and Exchange Commission, Fort Worth, Texas-based American (Nasdaq: AAL) said Wednesday that it intends to work with unions to adjust hourly base pay rates of all pilots and flight attendants. The impact on salary and benefits expenses will be roughly $230 million for 2017 and…