Eleven months after AirAsia Flight 8501 crashed under mysterious circumstances south of Borneo, taking with it the lives of 162 passengers and crew, we at last understand what happened: On Tuesday, Indonesia released a report revealing that the plane was doomed by a combination of minor mechanical glitches and pilot error. While this in itself would be grounds for concern, eerie similarities with another crash five years earlier suggest that an underlying vulnerability remains unaddressed in the worldwide air-travel system — one that could eventually have unexpected and far-reaching consequences for the driverless cars currently being developed by some of the world’s richest and most ambitious companies.
Flight QZ8501 took off from Surabaya, on the Indonesian island of Java, at 5:35 a.m. local time on December 28, 2014, bound for Singapore. Ahead lay a band of thunderstorms, some of them towering up to 44,000 feet high. After reaching the assigned cruising altitude of 32,000 feet, the flight crew called air-traffic control and requested a turn to the left to avoid a storm. Given permission, the pilots then asked to climb to 38,000 feet. Controllers denied that request, then soon afterward said the plane could go to 34,000 feet. But something had gone wrong. The pilots did not respond to the new clearance. Instead, without issuing a distress call or signal, the plane abruptly climbed, slowed, and banked into a steep turn. When it disappeared from radar, it was plummeting at a rate of more than 11,000 feet per minute.
For days it seemed as though the plane had simply vanished. Then, on December 30, the first bodies and debris were pulled from the ocean six miles from the plane’s last known location. More wreckage was recovered soon after, and on January 12, the black boxes were recovered from the ocean floor.
Given the proximity of the thunderstorms and the flight crew’s urgent efforts to avoid them, it seemed that weather was likely a major cause of the accident. Indeed, before the black boxes were found, Indonesia’s weather agency issued at 14-page report stating that most likely the plane had been brought down by icing in the thunderstorm cloud tops.
But as Tuesday’s report takes pains to emphasize, it turns out that weather had no direct bearing on what happened. Instead, it focuses on pieces of equipment located in the tail of the aircraft called the Rudder Travel Limiter Units, or RTLU.



