The European Union - Tuesday joined a growing number of nations that have suspended flights of Boeing 737 MAX jets, worried about the plane's safety after a deadly Ethiopian Airlines crash over the weekend.

Sunday's crash is the second fatal accident involving the newly-launched 737 MAX-8 aircraft in five months.

But for now- The U.S. Federal Aviation Administration and U.S. airlines are standing by Boeing and keeping the plane in the air.

Black box recorders were found at the crash site on Monday, but are yet to yield a cause.

Boeing said on Tuesday it has "full confidence" in the safety of its 737 MAX fleet.

But others are not as confident.

President Trump said in a tweet before he spoke with Boeing CEO Dennis Muilenberg, that he was worried airline technology had become too complex.

Tweeting: "Pilots are no longer needed, but rather computer scientists from MIT.

"I want great flying professionals that are allowed to easily and quickly take control of a plane." And lawmakers on both sides of the aisle called for the plane to be grounded, including Ted Cruz, the Republican head of the Senate panel that oversees aviation and Democratic presidential candidate Sen.

Elizabeth Warren.

Southwest, American and United Airlines all say they will keep flying the plane.

But U.S. passengers and flight attendants are nervous.

Flight attendant unions at the carriers have urged them to consider parking the plane until more is known.

U.S. Transportation Secretary Elaine Chao tried to calm nerves.

SOUNDBITE: U.S. TRANSPORTATION SECRETARY ELAINE CHAO (ENGLISH) SAYING: "If an issue that affects safety is identified, the department and FAA will not hesitate to take immediate and appropriate action." The disaster has wiped billions $27 Billion dollars from Boeing's market value in the stock's biggest two day fall in a decade.

For the families grieving the 157 people lost in the crash - it may be some time before they get any answers.

Ethiopian Airlines said it would take at least five days to start handing the remains of those killed back to their families.

But it could be weeks or months before all victims are identified.