​Following the second crash in less than six months of a Boeing 737 Max jet, China, which accounts for 20 percent of global 737 Max deliveries, is grounding its operating fleet.

The move comes after all 157 people aboard an Ethiopian Airlines flight bound from Addis Ababa to Nairobi, Kenya were killed Sunday morning in a fatal crash. That crash was the second in a little more than five months for the jet aircraft model, after Lion Air went down off the coast of Indonesia shortly after take-off, killing 189 people.

"A suspension in China is very significant, as this is a major market for Boeing," said Greg Waldron, Asia managing editor at aviation research firm FlightGlobal told reporters. “A formal investigation will need to be conducted into this new crash. It’s important not to speculate as to its causes. A final, conclusive report has yet to be issued in the case of the Lion [Air] crash. That said, having two crashes of a brand new type in a short time is an unprecedented state of events. It is inevitable that this will affect perceptions about the 737 MAX family.”

China is Boeing’s biggest client for this series and on a trajectory to become the world’s first trillion-dollar market for aircraft. Industry predictors hold that China is on track to require some 7,690 commercial jets to meet demand in the next two decades. A dozen Chinese airlines have ordered 180 of the planes, and 76 of them have been delivered, according Boeing in news reports. About 85% of Boeing's unfilled Chinese airline orders are for 737 MAX planes.

Boeing’s 737 series is the airline manufacturing company’s best selling product and has been so since the first Boeing 737 launched in 1967. The fourth generation, the 737 Max, made its debut in 2017 and Indonesia’s flagship discount carrier, Lion Air, became its first commercial operator. The Max has been a shiny bauble for airline companies as it incorporates more automation, and has a higher range (up to about 3,550 miles using less fuel.

But after the Lion Air crash, investigators learned that the 737 Max software can force the plane's nose down in certain situations in an effort to prevent stalling. However, many pilots say they were not aware of the system and may have lacked complete training on the new software.

Currently, no American carriers are making murmurs about grounding their Max fleets. American Airlines, Alaska Air, United Airlines, and Southwest Airlines have ordered a combined 548 of Boeing's 737 MAX jets, 65 of which have been delivered. Boeing has delivered about 350 737 Max planes and has orders for more than 5,000, according to various news reports.