United Airlines Pushes MAX Flights Back To 2020

United Airlines on Friday again pushed back the timeframe for resuming service on the Boeing 737 MAX, which still needs to be recertified by regulators after two deadly crashes.

United said it was removing MAX flights from its schedule until January 6. The previous plan had taken the planes out of service through December 19.

"Moving forward, we'll continue to monitor the regulatory process and nimbly make the necessary adjustments to our operation and our schedule to benefit our customers who are traveling with us," the company said in a statement.

The top-selling Boeing plane has been grounded since mid-March following crashes of Lion Air and Ethiopian Airlines planes that killed 346 people.

Boeing is targeting regulatory approval for the planes' return to service this year following upgrades but the aerospace giant has noted government authorities will have the final say.

The FAA has signaled the return of the plane could occur in stages by country in light of a lack of consensus among regulators.

But the US regulator has faced heavy scrutiny over its approval of the MAX a faced more questions on Friday.

A review of the MAX process by international regulators criticized the US agency for failing to stick to its own rules and not having sufficient manpower or expertise to oversee the plane's development, according to reports.