Washington (CNN) Add modern aviation technology to the list of technological advances the President of the United States distrusts.

"Airplanes are becoming far too complex to fly," President Donald Trump tweeted on Tuesday. "Pilots are no longer needed, but rather computer scientists from MIT. I see it all the time in many products. Always seeking to go one unnecessary step further, when often old and simpler is far better. Split second decisions are needed, and the complexity creates danger. All this cost for very little gain."

Trump's tweets come days after a Boeing 737 MAX 8 plane crashed , the second time in months that the new airplane model has wrecked minutes after takeoff, killing all on board. The crashes have raised questions about the role of a new software system installed on the plane, but investigators have yet to reach a conclusion about the cause.

The similar circumstances of both crashes have caused several countries and airlines to ground the 737 MAX 8 planes, but despite growing calls from US lawmakers to do the same -- and Trump's tweet on Tuesday morning -- the Federal Aviation Administration has yet to follow suit.

Trump and Boeing CEO Dennis Muilenburg spoke by phone on Tuesday after Trump's tweet, according to two sources familiar with the call, in the first known conversation between the Boeing CEO and the President since the Ethiopian Airlines plane crash on Sunday. The sources did not share details of their conversation.

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