(CNN) President Donald Trump and Boeing CEO Dennis Muilenburg spoke by telephone Tuesday, following Trump's tweet about how flying has become too complicated, according to two sources familiar with the conversation.

Muilenburg has talked to Trump frequently and appeared alongside him several times during the first two years of his presidency.

"Airplanes are becoming far too complex to fly. 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," Trump tweeted.

"Split second decisions are needed, and the complexity creates danger. All of this for great cost yet very little gain. I don't know about you, but I don't want Albert Einstein to be my pilot. I want great flying professionals that are allowed to easily and quickly take control of a plane!" he added.

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.

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