157 people were on board an Ethiopian Airlines flight bound for Nairobi, Kenya, when the Boeing 737 plane crashed just six minutes after takeoff.

This marks the second time in 5 months a plane with the 737 Max 8 engine has crashed. In October of 2018, a Lion Air flight crashed minutes after takeoff from Jakarta airport in Indonesia. All 189 people on board were killed.

As a result of these accidents, many airlines have decided to ground all planes featuring the 737 Max 8 engine, though experts warn it is not clear that the engine is the main cause of the latest tragedy.

Ethiopian Airlines pilots reported difficulty with the 737 Max 8 engine, a new model by Boeing that according to Jakarta-based aviation analyst Gerry Soejatman, is slightly different to the older version of the vehicle. In an interview with the BBC, Soejatman said the 737 Max’s “engine is a bit further forward and a bit higher in relation to the wing, compared to the previous version of the plane. That affects the balance of the plane”.

After the crash in Jakarta last year, investigators looking into the problems around the accident said the pilots of that flight had apparently struggled with the system designed to keep the plane from stalling. This feature is one of the new attributes of the 737 Max 8.

This new anti-stall feature forced the nose of the Lion Air flight down, while pilots grappled to correct the trajectory of the plane and point the nose upward. The anti-stall system continued to force the nose down, which findings by investigators suggest led to the crash of the Indonesian flight.

“It’s highly suspicious,” Mary Schiavo, the former Inspector General of the US Transportation Department, told CNN in an interview.

“Here we have a brand-new aircraft that’s gone down twice in a year. That rings alarm bells in the aviation industry, because that just doesn’t happen.”

According to Reuters, Boeing is expected to release a correction to the system by way of a software patch.