American Airlines raised its offer for a new pilot contract by more than $1 billion to match a preliminary deal last week between rival United Airlines and that carrier’s aviators.

The new offer from American Airlines would bring the four-year offer’s value to around $9 billion, and match United pay rates, backpay and other benefits such as sick time and life insurance, CEO Robert Isom said in a message to pilots on Friday.

Airlines and pilot unions had been negotiating new deals for years. Unions have won more bargaining power in the wake of Covid as the industry grapples with a prolonged pilot shortage just as travel demand recovered. Delta Air Lines pilots approved a new agreement in March for a deal that includes 34% raises over four years.

American’s pilots were scheduled to start voting on the current deal on Monday. The new offer includes 21% pay bonuses and pay on par with United and Delta, the Allied Pilots Association, their union, said Friday.

Captain Ed Sicher, the union president, said its leadership will weigh “whether management’s comprehensive proposal is worthy of a membership vote.”

Isom said that the company will return to negotiations if changes aren’t approved in time for the vote.

“We’ll return to the bargaining table and do what’s necessary to get to a deal. It just won’t be done quickly,” Isom said. “We run a complex business and any changes to what we agreed to — even small ones — may have a profound impact. Reconsideration of all of these items would take time.”