JetBlue CEO Robin Hayes will step down next month and will be replaced by the airline's president and chief operating officer, Joanna Geraghty, the company announced Monday.

Why it matters: Geraghty will be the first woman to lead a major U.S. airline carrier, AP notes.

• The change at the top comes as JetBlue defends a proposed $3.8 billion takeover of Spirit Airlines over antitrust objections from the U.S. Department of Justice, which has filed a lawsuit in an effort to block the bid.

The big picture: Hayes, who has been at the airline for nine years and will serve as a strategic advisor to the company over the coming months, said in a statement that it's "bittersweet to retire from this airline" that he loves.

• "However, the extraordinary challenges and pressure of this job have taken their toll, and on the advice of my doctor and after talking to my wife, it's time I put more focus on my health and well-being," added Hayes, who led the airline through the COVID-19 pandemic.
• Geraghty, who has been with JetBlue for nearly 20 years, said in a statement she's "looking forward to building on this momentum as we execute on our strategic initiatives, return to profitable growth, and generate sustainable value for our shareholders and all our stakeholders."

What's next: Hayes will remain on the board of directors until he retires on Feb. 12, when Geraghty will become CEO.