By Chun Han Wong

Chinese authorities said the pilot of a light aircraft that crashed into Beijing's tallest building last week had contemplated ending his life, portraying an incident that exposed security risks in the highly protected capital as the result of personal, not political, motivations.

In a social-media post published Thursday, the government of Beijing's Chaoyang district, where the crash happened, identified the pilot as a 66-year-old man, surnamed Liu, who died after flying a single-engine, two-seater propeller plane into a high-rise building.

The Chaoyang government said Liu had a history of chronic insomnia and anxiety, and that his diary contained repeated references to "ending his life." Investigators concluded that this was a case of "endangering public safety" caused by "personal reasons," the post said.

The plane struck Citic Tower, also known as China Zun, at around 6 p.m. local time on Friday. The 109-story skyscraper in Beijing's central business district holds the headquarters of one of China's earliest global conglomerates, and is located near some of the country's most upmarket shopping centers and the headquarters of state broadcaster China Central Television.

The tower, completed in 2018 and shaped to resemble a traditional Chinese wine vessel, is less than 5 miles east of Tiananmen Square and the leadership compound where top officials of China's Communist Party live and work. The incident happened days before the anniversary of the founding of the party.

Though the Chaoyang district statement discussed a potential motive for Liu's actions, it didn't address concerns about how a plane was able to fly into the heart of China's heavily fortified capital, through some of the country's most tightly controlled airspace.

As of August 2023, China had 3,200 registered general-aviation aircraft, according to a U.S. Department of Commerce report at the time — a minuscule number compared with the hundreds of thousands of such aircraft in the U.S.

Francis Chao, an American aviation consultant who has worked in China, said the incident will prompt Chinese regulators to tighten controls on general aviation in the country, given that it took place at a highly sensitive location "right at the emperor's feet." Even so, he expects Beijing to remain broadly supportive of efforts to develop what it calls the "low-altitude economy" — a reference primarily to commercial activities, including aircraft and drones, in airspace generally no higher than 1,000 meters.

In its Thursday disclosure, the Chaoyang government said Liu, a Beijing resident, was a freelance worker who lived alone following a divorce. In 2021, he obtained a license for flying light "sport" aircraft that can carry up to two people, before getting a private pilot license in 2024, the post said.

Liu took off from a general-aviation airport in eastern Beijing on the afternoon of the incident and proceeded to conduct formation and solo flying, the post said. While flying solo, Liu deviated from his designated airspace and dropped out of contact with the airport before crashing into Citic Tower.

Liu was flying an Aurora SA60L, registration number B-12PP, according to Chaoyang authorities. The number matched that seen in images of aircraft debris that circulated on social media after the crash.

Write to Chun Han Wong at chunhan.wong@wsj.com

Help is available: Reach the 988 Suicide & Crisis Lifeline (formerly known as the National Suicide Prevention Lifeline) by dialing or texting 988.