BA Boeing Co

By Jon Emont and Feliz Solomon 

The Sriwijaya Air jet that crashed on Saturday didn't fly for nearly nine months last year, with air travel severely reduced because of the coronavirus pandemic, Indonesia's transportation ministry said, as search crews pulled one of the plane's so-called black boxes from the Java Sea.

The Boeing Co. 737-500 was inspected and declared airworthy before resuming flying operations, the ministry said.

The Indonesian carrier's aircraft with 62 people on board went down minutes after taking off from the country's capital, Jakarta. There are believed to be no survivors.

Divers and search crew, who grappled with sharp debris and low underwater visibility, managed to recover the plane's flight-data recorder on Tuesday, an important early step in uncovering why SJ182 crashed.

The plane had stopped operating in late March, weeks after Indonesia announced its first Covid-19 case, the transportation ministry said. The aircraft began flying again on Dec. 19, after clearing an inspection by the ministry's Air Transportation Directorate General, the ministry said.

The plane conducted a total of 132 flights after it resumed flying, according to aviation data provider Flightradar24.

"This is pretty standard for this airline and this part of the world," said Ian Petchenik, a Flightradar24 spokesman. "Because aircraft are the main source of connectivity, there are a lot of short routes with high frequencies."

Its first flight after the long hiatus didn't carry passengers and was noncommercial, the ministry said. The first with passengers was on Dec. 22, 2 1/2 weeks before the crash.

The aircraft's certificate of airworthiness from the transport ministry is valid until Dec. 17, 2021, the transportation ministry said.

The ministry said it followed an airworthiness directive issued by the U.S. Federal Aviation Administration dated July 24 that required operators of some Boeing flight models, including the Boeing 737-500, to conduct an engine inspection before flying. On Dec. 2, Indonesia's air inspector gave the plane an engine-corrosion check.

Sriwijaya Air Chief Executive Jefferson Irwin Jauwena said Tuesday that since March, Sriwijaya Air had undergone a security and safety audit under the Basic Aviation Risk Standard program, which is run by the Flight Safety Foundation in Alexandria, Va. The audits look at several aspects, including safety- and quality-system management, manual operations, licensing, and supervision of aircraft and spare parts, he said.

A spokeswoman for Sriwijaya Air didn't immediately respond to requests for comment on whether the plane's prolonged inactivity might have affected its flightworthiness and what maintenance was undertaken when the plane resumed flights in December. The airline said earlier that the plane was in good condition before the crash.

"It's important that the full records be made public, to show where it was serviced, when and by whom," said Shukor Yusof, founder of Malaysia-based aviation consulting firm Endau Analytics. "I'm not questioning the reliability of these documents, but it would be really good if we could see a full list, a full history of this aircraft."

Some experts around the world have raised concerns that the lower frequency of air travel during the pandemic could impact air safety. Chow Kok Wah, a Singapore-based aviation consultant, said planes that have been grounded for longer periods than usual require unique inspection protocols. Investigators might look for explanations in the aircraft's maintenance records, he said.

Answers about what happened to the aircraft may start to emerge as investigators extract data from the recovered black box. The flight-data recorder collects information about how plane systems performed. The vast data it holds ranges from basic speed and altitude figures to flight-control inputs by the crew.

"Hopefully it goes smoothly and we can reveal the mystery about the cause of this accident," said Soerjanto Tjahjono, head of the national transportation committee, after the device was retrieved.

The recorder will be sent to a Jakarta laboratory run by the country's national transportation safety committee, where specialists will clean and dry it out before downloading the information, which is stored in binary format. That process is expected to take two to five days, followed by a deeper analysis of the data.

Investigators often can assess what likely transpired on board within a short period, though a detailed assessment typically takes months.

Search crews will continue their underwater hunt for the second black box -- the cockpit-voice recorder -- which captures pilot conversations. That can help investigators understand what the pilots were experiencing in the moments before the plane went down, and connect the dots with what they glean from the flight-data recorder. Both devices are important to help determine what caused the crash.

Investigators haven't revealed the focus of their probe. Based on a preliminary analysis, the head of the transportation safety committee said the plane is unlikely to have exploded in the air and instead likely broke apart when it crashed into the water at high speed.

Authorities arrived at that conclusion because the shattered aircraft's debris was contained in a limited area rather than scattered over large areas of water, and based on an analysis of radar signals.

Viriya Singgih contributed to this article.

Write to Jon Emont at jonathan.emont@wsj.com and Feliz Solomon at feliz.solomon@wsj.com

(END) Dow Jones Newswires

January 12, 2021 11:19 ET (16:19 GMT)

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