An Ethiopian Airlines Boeing 737-800 MAX crashed into the ground Sunday morning after taking off from Addis Ababa, killing all 157 people aboard. It’s the second time in six months this type of jet has crashed in the first few minutes of flight, resurfacing questions about the safety of the plane, which entered service in May 2017.

The Nairobi-bound plane, Flight 302, took off from Addis Ababa’s Bole International Airport at 8:38 am local time. It lost contact with the ground eight minutes later, according to a statement from the airline. Flight tracking site FlightRadar24 reports the jet’s vertical speed was unstable after takeoff.

The victims—eight crew members and 149 passengers—were of 35 nationalities, including 32 Kenyans, 18 Canadians, and eight Americans. The Ethiopian Civil Aviation Authority and Transport Authority are investigating the crash. As the plane was manufactured in the United States, the American National Transportation Safety Board will send a four-person team to assist, a spokesperson says. Boeing and the airline have both said they will assist with the investigation.

The senior captain on the Ethiopian flight, Yared Getachew, had logged more than 8,000 flight hours. The first officer, Ahmed Nur Mohammod Nur, had 200 flight hours, according to the airline, which also said that the plane underwent “rigorous first check maintenance” on February 4.

While authorities say it’s too early to speculate about what caused the crash, the situation is scarily reminiscent of the Lion Air crash that killed 189 people after plunging into the Java Sea last October, shortly after takeoff. That plane also showed an unstable vertical speed. The Indonesian Transportation Safety Committee found that Lion Air Flight 610 had an erroneous input from one of its angle-of-attack sensors. Afterward, Boeing issued a safety warning, advising airlines operating the 737 MAX to have their pilots review how to handle such readings. The Federal Aviation Administration then issued an Airworthiness Directive, making that advice mandatory for US airlines.

The angle-of-attack sensor indicates how much lift the plane’s wings are generating. When commercial jets detect an overly steep angle of attack, their safety systems automatically point the nose downward, to limit the chance of a loss of lift and to avoid an aerodynamic stall. As WIRED reported at the time, “If the readings are incorrect or inconsistent, both the automation and the humans can be confused into pushing further and further down while they’re trying to figure out what’s going on and what to do about it, causing the sharp nosedive.”
It’s grim news for Boeing, which designed the 737 MAX to replace the 737 as its most popular single-aisle jet. It’s the company’s fastest-selling plane ever: Boeing has taken 4,700 orders from more than 100 customers.