The pilots on both flights said that each airplane began to tilt down suddenly shortly after the pilots turned on an automated piloting system in the Max 8 aircraft. Both airplanes regained altitude soon after the autopilot was disconnected, according to a NASA database of safety reports that pilots voluntarily submit.

Last October, 189 people died after a Boeing 737 Max jet operated by Lion Air plunged into the Java Sea off the coast of Indonesia. The pilots of that flight reported that the plane’s nose kept pitching down dozens of times before it crashed. On Sunday, an Ethiopian Airlines Max 8 crashed in a field outside Addis Ababa shortly after takeoff, killing the 157 passengers on board.

While the Federal Aviation Administration has said there is not yet a link between the two crashes, China, Australia, Singapore, the European Union, and India have suspended 737 Max flights while investigators probe the reasons for Sunday’s crash. Boeing’s stock has fallen 11% this week amid concerns about the safety issues of one of its most popular planes.

The FAA, meanwhile, is standing firm on its decision not to ground 737 Max airplanes in the U.S. Southwest Airlines and American Airlines are both still flying their 737 Max 8s, with both airlines maintaining that the planes are safe. Unions representing airline attendants from both carriers are asking that the Max 8 planes be grounded.

In one of the two pilot reports made last year, an airline captain said that the co-pilot began calling out “Descending!” shortly after the plane was put on autopilot, the AP said. “With the concerns with the MAX 8 nose down stuff, we both thought it appropriate to bring it to your attention,” the captain wrote.

In the second report, the plane began losing between 1,200 and 1,500 feet per second only seconds after engaging the autopilot but corrected once the autopilot was turned off. The pilots talked it over later, “but can’t think of any reason the aircraft would pitch nose down so aggressively,” one of the pilots wrote.