United Airlines (UA), headquartered in Chicago, announced on Saturday that it has temporarily grounded all Boeing 737 MAX 9 aircraft in accordance with the requirements of the Federal Aviation Administration (FAA).

In a statement released on Saturday, United Airlines stated that it has temporarily suspended the service of all Boeing 737 MAX 9 aircraft for FAA required inspections. We are working with FAA to clarify the inspection process and the requirements for all MAX 9 aircraft to resume service.

On Friday, a Boeing 737 Max 9 aircraft of Alaska Airlines exploded at an altitude of 16000 feet, leaving a large hole, reducing cabin pressure, and grounding the UA.

This plane flying to Ontario, California made an emergency landing in Portland 20 minutes after takeoff.

The National Transportation Safety Commission and the Federal Aviation Administration have begun reviewing damaged aircraft. No information on possible reasons was provided.

On Saturday, the Federal Aviation Administration issued an emergency order for the 737 MAX aircraft line, grounding 171 aircraft at the international level.

This accident is the third major safety hazard of the line. The other two accidents were fatal shortly after its debut.

Boeing stated in a statement released on Saturday that it is "working hard to gather more information" and added that its "technical team is ready to support the investigation".

According to local media reports, there are 79 Boeing 737 MAX 9 aircraft in the UA fleet, of which approximately 33 have undergone necessary inspections as required by the FAA.