Delta Air Lines (DAL) can't debut its new plane, the Airbus A220, because there's no one at the FAA to sign off on it.
The new jet from Airbus, which is designed to replace less efficient regional jets, needs to get final certification from FAA inspectors before it can begin service.
"No customer impact is expected as a result of this equipment change and no flights will be canceled. The flights will be operated by other aircraft," said the airline.
Delta had warned last week that a delay was likely when it issued earnings. It estimated the shutdown would cost Delta $25 million in lost revenue if it continued through January. On Thursday, Southwest warned that the shutdown could cost it between $10 million and $15 million.
Earlier this week, Alaska Air (ALK) said it was forced to delay the start of passenger service at Paine Field, due to a lack of FAA approval as well. The airport, which is about 25 miles north of Seattle, hasn't had commercial passenger service in decades. The service had been due to start on Feb. 11. Now it will be delayed until at least March 4.