SINGAPORE -- Asian skies have become much safer in the past few years, but the crash of an airplane of Indonesian low-cost carrier Lion Air, the first major air accident in Southeast Asia in close to four years, is a stark reminder for the fast-growing industry that safety standards still need improving.

A shortage of trained pilots and engineers is the biggest challenge, and insufficient airport infrastructure is another, industry experts agree.

Lion Air's brand-new Boeing 737 Max 8 aircraft, with 189 passengers and crew aboard, plunged into the Java Sea on Oct. 29, soon after it left Jakarta bound for Pangkal Pinang, an Indonesian tourist island. Search and investigation continue, but all lives are presumed lost. 

At a time when the air travel market is expanding at breakneck speed, there is concern about safety being undermined. 

"Rapid expansion does cause problems if it is not handled very well," said Geoffrey Thomas, a veteran industry watcher who manages Airlineratings.com, an Australia-based airline safety review website. The biggest problem is finding and training pilots and engineers. "There are pressure points there, particularly for low-cost airlines," because the salaries paid by budget carriers are often lower than at their full service peers. "If you can't get the right staff, you may compromise and get staff who are not suited to the job," he said.

Greg Waldron, Asia managing editor of industry news and data provider Flightglobal, agreed, saying, "Unfortunately, the aviation industry is not as glamorous as it used to be 30-40 years ago, so attracting talent is tougher."

Lion Air group was founded in 1999 and started flying in 2000. It is expected to become one of the largest airline groups in Asia. It announced itself to the world in 2011, when it placed the largest order U.S. aircraft maker Boeing had ever received, a $21.7 billion deal for 230 planes. It made a splash again in 2013 with a $24 billion deal with Europe's Airbus for 234 A320s. According to an analysis by Airfinance Journal, the group has the second-most aircraft on order among Asia-Pacific airlines as of September this year, with 369 jets awaiting delivery. 

The budget airline, along with Malaysian rival AirAsia, led the expansion of the aviation market in Southeast Asia over the past decade serving the rising middle class, many of whom discovered the joy of flying for the first time. Close to 60% of total passenger capacity in the region is operated by LCCs. 

The crash was the first fatal accident for Lion Air since a failed landing accident in 2004 in Solo City, Central Java province, which claimed 25 lives. But between the two serious crashes, it had a spotty safety record, with a number of minor incidents as well as runway overruns reported. The most high-profile trouble came in 2013, when its flight to the tourist destination of Bali ended up in the water near the island's international airport. All 108 people on board were unharmed. Pilots with the airline have also been found in possession of methamphetamines in a spate of incidents.

For Southeast Asian carriers, it was the first major accident since the Indonesia AirAsia aircraft, carrying 162 people, crashed in December 2014. 

After the latest accident, Lion Air's technical director and four others, including the maintenance and engineering director, were temporarily replaced, in accordance with instructions from the Transport Ministry. It was not a permanent move but "a warning that they have to be responsible" in their positions, Transport Minister Budi Karya Sumadi said on Nov. 1.

The airline, however, has been improving its safety standards in recent years, judging by the result of audits by international bodies. In 2016, the European aviation authority lifted the flight ban on the airline after nine years. Lion Air passed the IATA Operational Safety Audit (IOSA), the global industry standard for airline operational safety, by the International Air Transport Association in February 2017, and completed a renewal audit this year, IATA said.

The audit and the lifting of the ban showed that the carrier has proper safety management processes in place and "in theory, they are practiced," said Harro Ranter, CEO of the Aviation Safety Network. Whether Lion Air was operating with a defective safety system, and the authorities and international bodies failed to detect it, are questions that cannot be answered as yet. "The Indonesian authority is responsible for the oversight of Lion Air on day-to-day operations, and it is hard for me to say if they should have done things differently," Ranter added.

The quality of an airline's pilots and engineers greatly affects its level of safety, regardless of a company's procedures or its certification by regulators. Japan Airlines apologized on Nov. 1, after one of its co-pilots was arrested in London for intoxication before a flight. The 42-year-old had passed the company's internal breath test, but was discovered to have a blood-alcohol level far exceeding the legal limit in a second test. The company admitted that the in-house test was likely to have been conducted improperly.

Lion Air's latest crash happened after the industry recorded the fewest accidents on record in 2017, both in the world and in the Asia-Pacific region. The number of accidents at Southeast Asian airlines "has been on a downward trend for the past 18 years," Ranter noted.

A number of Lion Air's incidents, such as overruns, have been attributed to Indonesia's underdeveloped airport infrastructure, including short runways, Thomas noted. "While [Indonesia] has made great improvement, there is a lot more to go yet on airport infrastructure development," he said.

In order to improve safety standards in the region, Waldron stressed that the airline companies have to create a safety culture, which he said can be "challenging" when the companies are aggressively growing and competing. "Transparency is the key," he said. Any incident, big or small, should be reported and shared publicly so that "the broader community can learn from it to improve safety."

Some countries in the region, however, still restrict access to such information, he noted, citing the example of Singapore's regulator, which did not make public a transcript of the full cockpit conversation during an engine fire in 2017. No one was injured in that incident. 

Nikkei staff writer Shotaro Tani in Jakarta contributed to this story.