Transcript for Trump issues emergency order grounding all 737 Max 8, Max 9 planes

First, president trump tonight and his emergency ordering grounding all Boeing 737 max 8s and 9s tonight. President trump announcing the decision from the FAA citing new evidence. Tonight, what we have now learned. Why his decision today and that order taking effect immediately. Leading to confusion. Tonight, news pilots and some first officers had anonymously shared their own concerns during some domestic flights. ABC's David Kerley covers aviation and leads us off tonight. Reporter: This southwest 737 max 8 flight, one of the last, as the U.S. Tonight joined the rest of world. We're going to be issuing an emergency order of prohibition to ground all flights of the 737 max 8 and the 737 max 9. The safety of the American people and all people is our paramount concern. Reporter: Immediately, three U.S. Airlines told to stop flying their 737 MAXS. We got a call from your company. You need to contact them. Southwest 410, we've been directed to return to the gate. Reporter: This max 8 towed from the gate and parked. One of 72 idled. The federal government was under public pressure for days, having watched China, Europe and today, Canada, ground aircraft. Flight maps from last week now showing the max's disappearing as they were parked. The reason, similarities between Sunday's crash in Ethiopia which killed 157, and the lion air crash in Indonesia less than five months earlier. Both flights, with the nose moving erratically up and down right after takeoff. A refinement of tracking data from satellites overnight, according to the FAA, and evidence from this debris field in Ethiopia, convinced the agency there are enough similarities in these flights that they grounded the fleet. Does this mean the two crashes are related? It does not mean the two crashes are related but they're close enough that it's worth saying stop flying these airplanes until we get the black boxes out. Reporter: Those two black boxes, found two days ago in Ethiopia, are damaged. The delay in extracting data was part of the reason for the U.S. Grounding. Tonight, those boxes will be flown to France. That data should confirm if the crashes are related and whether the fastest selling jetliner ever has a problem. Already, Boeing is working a software fix for one of the contributing factors in the lion air crash, and while there have been no documented cases of this erratic behavior on a U.S. Flight, a pilot and a first officer posted on anonymous message boards that their 737 max nosed down when the auto pilot was engaged. Tonight, nearly all 370 of this brand-new jetliner are sitting on the ground. Passengers landing today, reacting to the news. He said, all flights are grounded. We'll return to gate. All right, David Kerley live tonight. David, you reported that Boeing is working on that fix you mentioned after what happened in the first crash in Indonesia that nose-dive in that crash. Then the Wall Street journal suggesting that fix might have been delayed by the government shutdown but tonight the FAA pushing back on that? Reporter: I asked the FAA Ed a min stray or the directly whether or not the government shutdown slowed down that software fix and he told me that has not. It will be several weeks before it's ready. David, that's a max 8 that's going nowhere. David Kerley leading us off. David, thank you. I want to bring in Jonathan Karl. As we look at those pictures at airports across the country. Lot of passengers already alarmed are going to wonder after France, Germany, uk, all grounded the jets, was the U.S. The last to ground the planes. I'm told by a senior white house official the decision was initially made this morning not to ground the planes because there was no information with any fundamental problem with the Boeing 737 max. That changed mid-day when they became aware of that new satellite data suggesting a possible link between the Ethiopia and that early crash. The FAA and the department of transportation made a call to ground them. Jon Karl at the white house. Thank you We're also following what authorities are calling

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