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.

The officials did not share details of their conversation, but both confirmed the call to CNN. Later, a Boeing spokesman said Muilenburg “reiterated to the President our position that the MAX aircraft is safe.”

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’s tweet, though, cast aspersions on more than just the 737 MAX 8’s potentially faulty new anti-stall system that may have caused the nose of both planes to erroneously and fatally dip downward. He called into question the broad spectrum of sweeping technological advances that have made airplanes much safer in recent decades.

It’s the first known conversation between the Boeing CEO and the President since the most recent plane crash.