On Monday, Boeing launched a series of long-delayed aviation tests of its upgraded 737 MAX with inspectors manning the controls, aiming to gain clearance and restore its image after tragic crashes that overturned its leaders and grounded the plane globally.

British pilots from the US FAA and Boeing landed around a quarter past 2 p.m. local time at the King County International Airport following a round trip to eastern Washington that included a high-speed system check and other maneuvers over nearly three hours.

The flight was the first of three, all scheduled to take place next week, which will be used by the FAA to assess whether the company has resolved the issues with the aircraft and whether it can go back to regular operation.

The rigors of the flight testing campaign go beyond the previous test flights of the American multinational corporation, completed in a matter of hours on a single day, said industry sources.

After its landing at Grant County International Airport, in Moses Lake, Washington, the plane was back in the air at the time of publication. Based on flight plans, the plane was scheduled to fly back to Boeing Field.

In a Sunday email to congressional personnel, the FAA disclosed that the test flights were carried out to begin after regulators finalized a lengthy evaluation of the aircraft's system safety that Boeing submitted, Bloomberg News reported. But the agency stated that a number of major tasks remain before it will allow the 737 Max to return to flight operations.

News of Boeing's certification test sent its shares climbing as much as 11 percent, to $188.25, around Monday afternoon. The pair of 737 Max tragedies in Indonesia and Ethiopia triggered an immense crisis for Boeing, which has also struggled in recent months from falling demand for air travel due to the ongoing global health crisis.

The company's preparation has included hundreds of hours inside a 737 Max flight simulator at Boeing's Longacres facility in Renton, Washington, and hundreds of hours more in the air on the same test aircraft without FAA officials onboard. At least one of those practice flights included the same testing procedures conducted on Monday.

Boeing did not publicize Monday's flight tests, stating that the FAA was in charge of the process. Boeing Field's business-as-usual ambiance underscored a major change in the company's communication strategy on the controversial 737 MAX since 2019 when its ties with the Federal Aviation Administration soured when it released public statements predicting the timeframe for the plane's return.