Preliminary evidence suggests the crash of a China Eastern Airlines Corp. jet in March may be the latest such tragedy, a person familiar with the investigation said. If confirmed, that would make it the fourth since 2013, bringing deaths in those crashes to 554. So as aircraft become more reliable and pilots grow less susceptible to errors, fatalities caused by murder-suicides are becoming an increasingly large share of the total. While intentional acts traditionally aren’t included in air-crash statistics, they would be the second-largest category of deaths worldwide if they were, according to data compiled by Bloomberg. By comparison, 1,745 people died as a result of pilot error, mechanical failures or other causes on Western-built jets from 2012 through 2021. “It’s scary,” said Malcolm Brenner, a former human-behavior investigator with the US National Transportation Safety Board who worked on the probe of the 1999 EgyptAir Flight 990 crash, which was found to be an intentional act. “It is a major cause of concern. It’s one the industry needs to address.” So far, however, these rare but deadly acts have defied simple solutions. While improving mental-health care is a priority, those who have chosen to kill themselves and scores of others at the same time on jetliners mostly didn’t reveal any clues beforehand to coworkers, friends or family. And because of the taboo nature of suicide, the cases create unique political and cultural challenges, at times leaving such events shrouded in mystery or open to dispute. The probe into Malaysia Airlines Flight 370’s disappearance over the Indian Ocean in 2014 found it was likely flown there on purpose, for example, but the Malaysian government’s report contains no information on who may have done so or why. The risk of dying on an airliner has declined significantly in recent decades as a result of innovations in safety equipment, aircraft reliability and pilot training. After 5,005 people died on Western-built jets from 2001 through 2010, the total fell to 1,858 the next decade, according to data compiled by Boeing Co., AviationSafetyNetwork and accident reports. The odds of being on a plane involved in a fatal accident was about one in 10 million, according to Boeing. But deaths attributed to pilot suicides bucked that trend, actually moving upward, according to data compiled by Bloomberg. If the China Eastern crash is confirmed as the latest such suicide, it will mean that deaths due to intentional acts have exceeded all other causes since the start of 2021. So far, Chinese authorities have revealed few specifics about what led the China Eastern jet carrying 132 people to crash March 21. The flight, a Boeing 737-800 from Kunming to Guangzhou, was cruising at about 29,000 feet when it suddenly dove at high speed, according to Flightradar24 data. Surveillance videos show it hurtling nose-down toward the ground.  Government authorities and Boeing haven’t announced any potential safety issues with the plane since then, suggesting no systemic faults have been uncovered. Preliminary information from the jet’s crash-proof data recorder indicates that someone in the cockpit initiated the dive, said a person familiar with the probe who wasn’t authorized to speak about it. The likelihood the crash was intentional was earlier reported by the trade publication Leeham News and Analysis as well as the Wall Street Journal. China’s embassy in Washington didn’t respond directly to questions about whether the crash was intentional. Investigators are conducting the probe “in a science-based, meticulous and orderly manner” and will release information “in a timely and accurate fashion,” the embassy said in an email. As with any crash investigation, it can take months or years to conduct the tests and analysis needed to pinpoint a cause and rule out even the most remotely possible system failures. In addition to the Malaysian plane lost with 239 peop