WASHINGTON: China has issued visas to American investigators and technical advisers to support its investigation into last week’s deadly crash of a China Eastern Airlines Boeing 737-800 in that country, the US National Transportation Safety Board said on Tuesday.

“The team hopes to depart this week,” the NTSB said in a tweet.

In addition to NTSB investigators, China has issued visas to technical advisers from the Federal Aviation Administration, Boeing Co. and 737-800 engine maker CFM, the NTSB said.

It is still unclear whether the US team will need to quarantine in China under its COVID-19 protocols, the NTSB said, adding that the issue is still under discussion. China has been experiencing a surge in coronavirus cases.

The plane crashed into a mountainside in southern China on March 21, killing all 132 people onboard, in mainland China’s deadliest aviation disaster in 28 years. Recovery crews on Sunday found the second black box - the flight data recorder - in the wreckage. The NTSB has been in regular contact with the Civil Aviation Administration of China since the crash. Under an international agreement, the NTSB has the right to participate since the plane was designed and built in the United States.

FAA Administrator Steve Dickson told reporters on Tuesday he was encouraged by indications that China is following its obligations under that treaty.

“We’re ready to go,” Dickson said, but added: “We’re not over yet — so that needs to happen.” He noted there were ongoing discussions between China and the United States about outstanding issues including China’s COVID-19 protocols.

Jet engine maker CFM is a joint venture between General Electric and France’s Safran.