The U.S. Federal Aviation Administration on Wednesday afternoon grounded all remaining Boeing Max 8s and Max 9s just hours after Canada moved to ban the models from its airspace based on new satellite data that suggests similarities between Sunday’s crash of Ethiopian Flight 302 and the October 29 crash of Lion Air Flight 610. In its own statement, the FAA said it based its decision on new evidence collected at the site of Sunday’s crash outside Addis Ababa and “newly refined” satellite data. American Airlines, Southwest Airlines, and United Airlines stood as the last operators of the type following moves by the rest of the world’s aviation safety authorities to suspend their use into and over their territories. U.S. President Donald Trump announced the "emergency" order at about 2:30 pm Washington time.
The move by the U.S. marked an abrupt reversal after the FAA on Tuesday said its latest review showed “no systemic performance issues” and no basis for grounding the aircraft. However, a chorus of calls for grounding the airplanes by U.S. lawmakers on Tuesday and Wednesday along with Trump’s own stated misgivings placed pressure on aviation authorities.
Senator Richard Blumenthal of Connecticut suggested that the government shutdown earlier this year might have interrupted the FAA’s work with Boeing on releasing a planned software upgrade meant to mitigate the suspected problem that led to the October crash of the Lion Air flight into the Java Sea, killing 189 people. The FAA, however, until Wednesday afternoon stood by its decision only to issue a Continued Airworthiness Notification to the International Community (CANIC) that reiterates directives arising from the Lion Air crash.
“External reports are drawing similarities between this accident and the Lion Air Flight 610 accident on October 29, 2018,” said the FAA. “However, this investigation has just begun and to date, we have not been provided data to draw any conclusions or take any actions.”
The CANIC noted that the FAA planned to issue an airworthiness directive (AD) next month that codifies certain flight control design changes underway at Boeing. The design changes include activation and angle-of-attack signal “enhancements” and a maximum command limit of the maneuvering characteristics augmentation system (MCAS). Meant to improve pitch response at high angles of attack and prevent pilots from raising the airplane’s nose too high, the MCAS in the 737 Max 8 and Max 9 does not appear in the 737 NG. Engineers made the change to address differing stall characteristics in the Max resulting from its larger and heavier CFM Leap-1B engines. The MCAS can, however, force the airplane into a dive under circumstances such as faulty inputs from its angle-of-attack sensor, potentially leading to a crash, according to a November 7 emergency airworthiness directive issued by the FAA.
For its part, Boeing said it recommended to the FAA on Wednesday to ground the fleet. “Boeing continues to have full confidence in the safety of the 737 Max,” it said. “However, after consultation with the U.S. Federal Aviation Administration (FAA), the U.S. National Transportation Safety Board (NTSB), and aviation authorities and its customers around the world, Boeing has determined—out of an abundance of caution and in order to reassure the flying public of the aircraft’s safety—to recommend to the FAA the temporary suspension of operations of the entire global fleet of three hundred seventy-one 737 Max aircraft.
“Boeing makes this recommendation and supports the decision by the FAA,” it concluded.