Boeing 737 Max airplanes sit parked at the company's production facility on November 18, 2020 in Renton, Washington. Photo: VCG

The three mandatory prerequisites China has set for Boeing's 737 MAX to be back in service in the country will remain in effect, aviation industry watchers said on Thursday, following reports of a 737 MAX test jet heading to China.

There's still a way off for the flight ban to be lifted in China, the first to ground the narrow-body airliner in the aftermath of two MAX crashes in the world, they said.

A 737 Max test plane departed for China on Wednesday as part of Boeing's efforts to return to the Chinese market, according to Reuters, which cited unidentified sources.

"Boeing and China regulators have scheduled re-certification flights and testing in the coming days," Reuters reported. 

The plane is due to arrive at Shanghai Pudong International Airport on Saturday, ahead of a simulator test on Sunday and an initial flight test in China on August 11 if all goes as planned, the report said.

So far, it seems that Boeing has finished with the accident investigation while proposed modifications to the aircraft that are needed to prove effective are coming across as most troublesome, Wang Yanan, chief editor of Beijing-based Aerospace Knowledge magazine, told the Global Times on Thursday.

The modification effort will involve not only the required documentation but also the actual test flights, which mean either Chinese officials going to the US or the flights being conducted in China, according to Wang. 

The testing, if confirmed, would be a significant move toward lifting the ban by China's regulators.

Such test flights are not technically complex, but they will require negotiating efforts from both China and the US, as it concerns the selection of the arrival airport, especially factoring in the current strict anti-coronavirus requirements, Wang said.

Such test flights might continue for three to six months, while the flight evaluation and the test report writing and the approval of the results from both China and the US would be a lengthy process, he continued.

Progress on the re-certification test flights won't automatically be translated into the lifting of the flight ban, analysts said, pointing to the three mandatory requirements as the conditions for a comeback of the aircraft in China.

"China's civil aviation authorities always uphold three principles: First, aircraft alteration must be approved for airworthiness. Second, pilots must be fully and effectively retrained. Third, the conclusion of the investigation of the two fatal accidents must be clear and the improvement measures effective," Chinese Foreign Ministry Spokesperson Zhao Lijian said at a press conference in mid-June.

Only when the plane manufacturer fulfills such prerequisites, will the country consider allowing it to fly again, Lin Zhijie, a market watcher, told the Global Times on Thursday.

China will also verify the qualification of the testing based on the flights and modifications having been made, said Wang.

As for pilot retraining, Boeing can have it done simultaneously when it makes headway to prove its aircraft is airworthy, Wang said. 

"Boeing continues to work with global regulators as they complete their validation processes in order to better understand enhancements to the airplane. We refer you to the appropriate regulator for any details," the US plane-maker said in a statement sent to the Global Times on Thursday.

The Civil Aviation Administration of China didn't reply to a request for comment as of press time.