Two major U.S. airlines announced plans Friday to pull the Boeing 737 Max from their schedules into the march.
The move raises the prospect the plane could be out of service for nearly a full year.
The Max was grounded by regulators worldwide earlier this year after two fatal crashes killed nearly 350 people.
The Federal Aviation Administration issued the order on March 13th.
Southwest airlines, which operates the largest U.S.-based fleet of Boeing 737 Max jets, announced Friday it anticipates the plane returning to service on March 6th, 2020.
It had previously removed it from its flight schedules through early February.
American Airlines also announced that it expects the max to begin flying again on March 5th.
It had expected to fly it again in early January.