737 Max 8 Planes: 5 Questions About Boeing Model

After two deadly plane crashes involving the same Boeing model, several countries have moved to ground the airliner but aviation officials in the United States have not issued any such directive —even as pressure mounts on the FAA to stop the Boeing 737 Max 8 planes from flying. On Tuesday, the FAA said that thus far, its review "shows no systemic performance issues and provides no basis to order grounding the aircraft."

On Sunday, an Ehtiopian Airlines flight crashed shortly after takeoff, killing all 157 people on board. The plane flying from Addis Ababa in Ethiopia to Nairobi in Kenya was a Boeing 737 Max 8 plane, the same model as the Lion Air flight that crashed in October 2018.

According to The New York Times, data recovered from the Lion Air plane found that the plane's nose was repeatedly forced down more than 12 times while the flight was in the air. The Times reported that the black box data appeared to back the theory that there was an issue with a computerized system installed on the plane.

The FAA and the NTSB are both supporting investigators in Ethiopia with the probe into Sunday's plane crash. The FAA says that while external reports have drawn similarities between the Sunday crash and the Lion Air crash in April, their investigation has just begun and they have not been provided data to draw any conclusions or to take action. The agency also issued a continued airworthiness notification for the Boeing 737-8 and Boeing 737-9 planes.

Here are 5 answers to questions about the Boeing 737 Max planes.

How many 737 Max 8 planes fly in the U.S.?

According to the FAA, there are 74 737 Max 8 and 737 Max 9 airplanes registered to three U.S. airlines — American Airlines, Southwest and United. The Times reported that only American and Southwest fly the Boeing 737 Max 8 model specifically.

You can check out FligthAware's live map of the 737 Max 8 models in U.S. airspace here.

Who is pressuring the FAA to ground the planes in the U.S.?

Among those calling on the FAA to ground the model in the U.S. are Democrat U.S. Sens. Elizabeth Warren of Massachusetts, Dianne Feinstein of California and Richard Blumenthal, of Connecticut. Freshman Utah Sen. Mitt Romney, a Republican, has also called on the FAA to ground the planes.

Also on Tuesday, former transportation secretary Ray LaHood said the U.S. should ground the 737 Max planes.

Consumer Reports also called on the FAA and the airlines flying the planes to ground the 737 Max 8 models.

"U.S. carriers–including American and Southwest–need to do what governments and airlines around the globe have done and temporarily ground these airplanes," William J. McGee, aviation adviser for Consumer Reports, said in a statement. "These two domestic carriers operate 58 Boeing 737 MAX 8 planes on hundreds of flights daily. Telling the public that the airplane is airworthy, as the FAA has done, without offering further explanation, does far too little to relieve the uncertainty and fear created by these two tragedies."

The FAA said that other civil aviation authorities have not provided any data to them that would warrant action.

What is the FAA's latest statement?

On Tuesday evening, the FAA issued the following updated statement:

While it has not grounded the plane models, the FAA said if its data review of the Ethiopian Airlines crash finds any issues affecting the continued airworthiness of the aircraft, it will take immediate and appropriate action.

What has Boeing said?

In a statement on Tuesday, the company said it has "full confidence" in the safety of the 737 Max.

"The United States Federal Aviation Administration is not mandating any further action at this time, and based on the information currently available, we do not have any basis to to issue new guidance to operators," the statement said.

Have planes ever been grounded in the U.S. before?

When LaHood served as tranportation secretary under President Barack Obama, he ordered all Boeing Dreamliners to be grounded in 2013 due to battery problems.

The Associated Press contributed to this report.