Safety reports filed last year in a NASA database reveal that at least two U.S. flights had reported problems after engaging the autopilot systems on Boeing's 737 Max 8 planes.

According to the cases, the pilots reported the nose of their aircraft dipping downward sharply shortly after switching on an autopilot feature, but both planes were able to regain control after the pilots had switched it off, the Associated Press reported Tuesday.

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“With the concerns with the MAX 8 nose down stuff, we both thought it appropriate to bring it to your attention,” one of the pilots wrote in a report, allegedly referencing the Lion Air crash in Indonesia that killed 189 people in 2018. The co-pilot of another Boeing 737 Max 8 had said that neither he/she nor the pilot could "think of any reason the aircraft would pitch nose down so aggressively" after the nose of their flight pitched downward after switching on the autopilot.

In both cases, the plane's automated audio warning system engaged once the plane began descending.

The pilots, who gave their findings as part of a voluntary safety report, were not identified, nor were the airlines or the specific flights on which the incidents occurred.

The Associated Press report, compiled by David Koenig and Michael Sisak, comes amid concerns over the safety of Boeing 737 Max 8 jets following the crash of Ethiopian Airlines Flight 302.

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Their report notes, however, that the pilots did not link the incidents to the plane's anti-stall system, which is being investigated as a factor in the crash of the Lion Air flight in October. Following that incident, investigators with the Indonesia National Transportation Safety Commission blamed the automatic safety system as one contributing factor, reporting that pilots struggled to override its continuous attempts to force the plane’s nose downward.

Following that incident, had reportedly informed its customers of two switches in the cockpit which would have disabled the faulty safety feature, according to Bloomberg.

U.S. carriers including Southwest and American Airlines confirmed to Fox News that the carriers would still be utilizing the Boeing 737 Max 8 planes amid the investigation into the Ethiopian Airlines Flight 302, which crashed on Sunday, killing all 157 people on board.

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Acting FAA administrator Daniel K. Elwell said the administration is continuing to "review extensively" the data from the investigation, but thus far has found "no systemic performance issues" that would necessitate grounding the Boeing 737 Max 8 in the United States. If any issues of "continued airworthiness" are determined, Elwell says the FAA will take "immediate and appropriate action."

The Associated Press contributed to this report.