The US Department of Transportation (DOT) has given Alaska Airlines permission to close on its $1.9 billion acquisition of Hawaiian Airlines, after the carriers agreed to maintain key Hawaiʻi routes and adopt consumer protections. This exemption allows the carriers, which are respectively the fifth and 10th largest domestic airlines, to finalize their merger while maintaining separate operations until DOT rules on their transfer application.

DOT said the carriers have agreed to protect frequent flyer miles, to ensure HawaiianMiles and Alaska Mileage Plan miles retain their value at a 1:1 ratio after the merger. In addition, Alaska and Hawaiian will need to maintain "robust" levels of service for critical Hawaiian inter-island passenger and cargo service and the continental United States, ensure competitive access to Honolulu airport, offer fee-free family seating, lower costs for service members and their families, and provide alternative compensation for delays and cancellations, according to the agreement.

Alaska Airlines said on Tuesday that these commitments align with the plans it had last year when it signed the transaction and "do not impact the synergies of the deal, which will enhance competition and expand choice for consumers."

Until DOT completes its review of the transfer application, Alaska and Hawaiian must operate independently. If the transfer is approved, these protections will be in place for six years.

"We look forward to formally welcoming Hawaiian Airlines' guests and employees into Alaska Air Group," said Alaska Air Group CEO Ben Minicucci. "We sincerely appreciate the exceptional care and service that employees of both companies have continued to show for one another and our guests throughout this process, and the support of both airlines' labor unions, as we proceed to realize the vision for this combination and build a stronger future together."

The exemption order and agreement can be found here. More information about the combined organization will be shared in the coming days.